Ion-exchangeable mixed alkali aluminosilicate glasses

ABSTRACT

A glass composition includes from 55.0 mol % to 75.0 mol % SiO2; from 8.0 mol % to 20.0 mol % Al2O3; from 3.0 mol % to 15.0 mol % Li2O; from 5.0 mol % to 15.0 mol % Na2O; and less than or equal to 1.5 mol % K2O. The glass composition has the following relationships: Al2O3+Li2O is greater than 22.5 mol %, R2O+RO is greater than or equal to 18.0 mol %, R2O/Al2O3 is greater than or equal to 1.06, SiO2+Al2O3+B2O3+P2O5 is greater than or equal to 78.0 mol %, and (SiO2+Al2O3+B2O3+P2O5)/Li2O is greater than or equal to 8.0. The glass composition may be used in a glass article or a consumer electronic product.

RELATED APPLICATIONS

This application claims the benefit of priority of U.S. ProvisionalApplication Ser. No. 62/591,958 filed on Nov. 29, 2017, the contents ofwhich are relied upon and incorporated herein by reference in theirentirety.

BACKGROUND Field

The present specification generally relates to glass compositionssuitable for use as cover glass for electronic devices. Morespecifically, the present specification is directed to mixed alkalialuminosilicate glasses that may be formed into cover glass forelectronic devices by fusion drawing.

Technical Background

The mobile nature of portable devices, such as smart phones, tablets,portable media players, personal computers, and cameras, makes thesedevices particularly vulnerable to accidental dropping on hard surfaces,such as the ground. These devices typically incorporate cover glasses,which may become damaged upon impact with hard surfaces. In many ofthese devices, the cover glasses function as display covers, and mayincorporate touch functionality, such that use of the devices isnegatively impacted when the cover glasses are damaged.

There are two major failure modes of cover glass when the associatedportable device is dropped on a hard surface. One of the modes isflexure failure, which is caused by bending of the glass when the deviceis subjected to dynamic load from impact with the hard surface. Theother mode is sharp contact failure, which is caused by introduction ofdamage to the glass surface. Impact of the glass with rough hardsurfaces, such as asphalt, granite, etc., can result in sharpindentations in the glass surface. These indentations become failuresites in the glass surface from which cracks may develop and propagate.

Glass can be made more resistant to flexure failure by the ion-exchangetechnique, which involves inducing compressive stress in the glasssurface. However, the ion-exchanged glass will still be vulnerable todynamic sharp contact, owing to the high stress concentration caused bylocal indentations in the glass from the sharp contact.

It has been a continuous effort for glass makers and handheld devicemanufacturers to improve the resistance of handheld devices to sharpcontact failure. Solutions range from coatings on the cover glass tobezels that prevent the cover glass from impacting the hard surfacedirectly when the device drops on the hard surface. However, due to theconstraints of aesthetic and functional requirements, it is verydifficult to completely prevent the cover glass from impacting the hardsurface.

It is also desirable that portable devices be as thin as possible.Accordingly, in addition to strength, it is also desired that glasses tobe used as cover glass in portable devices be made as thin as possible.Thus, in addition to increasing the strength of the cover glass, it isalso desirable for the glass to have mechanical characteristics thatallow it to be formed by processes that are capable of making thin glassarticles, such as thin glass sheets.

Accordingly, a need exists for glasses that can be strengthened, such asby ion exchange, and that have the mechanical properties that allow themto be formed as thin glass articles.

SUMMARY

According to a first embodiment, a glass composition comprises: fromgreater than or equal to 55.0 mol % to less than or equal to 75.0 mol %SiO₂; from greater than or equal to 8.0 mol % to less than or equal to20.0 mol % Al₂O₃; from greater than or equal to 3.0 mol % to less thanor equal to 15.0 mol % Li₂O; from greater than or equal to 5.0 mol % toless than or equal to 15.0 mol % Na₂O; and less than or equal to 1.5 mol% K₂O, wherein Al₂O₃+Li₂O is greater than 22.5 mol %, R_(2O)+RO isgreater than or equal to 18.0 mol %, R₂O/Al₂O₃ is greater than or equalto 1.06, SiO₂+Al₂O₃+B₂O₃+P₂O₅ is greater than or equal to 78.0 mol %,and (SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O is greater than or equal to 8.0.

According to a second embodiment, a glass article comprises: a firstsurface; a second surface opposite the first surface, wherein athickness (t) of the glass article is measured as a distance between thefirst surface and the second surface; and a compressive stress layerextending from at least one of the first surface and the second surfaceinto the thickness (t) of the glass article, wherein a central tensionof the glass article is greater than or equal to 30 MPA, the compressivestress layer has a depth of compression that is from greater than orequal to 0.15t to less than or equal to 0.25t, and the glass article isformed from a glass comprising: from greater than or equal to 55.0 mol %to less than or equal to 75.0 mol % SiO₂; from greater than or equal to8.0 mol % to less than or equal to 20.0 mol % Al₂O₃; from greater thanor equal to 3.0 mol % to less than or equal to 15.0 mol % Li₂O fromgreater than or equal to 5.0 mol % to less than or equal to 15.0 mol %Na₂O; and less than or equal to 1.5 mol % K₂O, wherein Al₂O₃+Li₂O isgreater than 22.5 mol %, R₂O+RO is greater than or equal to 18.0 mol %,R₂O/Al₂O₃ is greater than or equal to 1.06, SiO₂+Al₂O₃+B₂O₃+P₂O₅ isgreater than or equal to 78.0 mol %, and (SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O isgreater than or equal to 8.0.

According to a third embodiment, a glass article comprises: a firstsurface; a second surface opposite the first surface, wherein athickness (t) of the glass article is measured as a distance between thefirst surface and the second surface; and a compressive stress layerextending from at least one of the first surface and the second surfaceinto the thickness (t) of the glass article, wherein a central tensionof the glass article is greater than or equal to 60 MPa, the compressivestress layer has a depth of compression that is from greater than orequal to 0.15t to less than or equal to 0.25t, and the glass article hasa composition at a center depth of the glass article comprising: fromgreater than or equal to 55.0 mol % to less than or equal to 75.0 mol %SiO₂; from greater than or equal to 8.0 mol % to less than or equal to20.0 mol % Al₂O₃; from greater than or equal to 3.0 mol % to less thanor equal to 15.0 mol % Li₂O from greater than or equal to 5.0 mol % toless than or equal to 15.0 mol % Na₂O; and less than or equal to 1.5 mol% K₂O, wherein Al₂O₃+Li₂O is greater than 22.5 mol %, R₂O+RO is greaterthan or equal to 18.0 mol %, R₂O/Al₂O₃ is greater than or equal to 1.06,SiO₂+Al₂O₃+B₂O₃+P₂O₅ is greater than or equal to 78.0 mol %, and(SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O is greater than or equal to 8.0.

Additional features and advantages will be set forth in the detaileddescription which follows, and in part will be readily apparent to thoseskilled in the art from that description or recognized by practicing theembodiments described herein, including the detailed description whichfollows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description describe various embodiments and areintended to provide an overview or framework for understanding thenature and character of the claimed subject matter. The accompanyingdrawings are included to provide a further understanding of the variousembodiments, and are incorporated into and constitute a part of thisspecification. The drawings illustrate the various embodiments describedherein, and together with the description serve to explain theprinciples and operations of the claimed subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 schematically depicts a cross section of a glass havingcompressive stress layers on surfaces thereof according to embodimentsdisclosed and described herein;

FIG. 2A is a plan view of an exemplary electronic device incorporatingany of the glass articles disclosed herein; and

FIG. 2B is a perspective view of the exemplary electronic device of FIG.2A.

DETAILED DESCRIPTION

Reference will now be made in detail to alkali aluminosilicate glassesaccording to various embodiments. Alkali aluminosilicate glasses havegood ion exchangeability, and chemical strengthening processes have beenused to achieve high strength and high toughness properties in alkalialuminosilicate glasses. Sodium aluminosilicate glasses are highly ionexchangeable glasses with high glass formability and quality. Thesubstitution of Al₂O₃ into the silicate glass network increases theinterdiffusivity of monovalent cations during ion exchange. By chemicalstrengthening in a molten salt bath (e.g., KNO₃ and/or NaNO₃), glasseswith high strength, high toughness, and high indentation crackingresistance can be achieved.

Therefore, alkali aluminosilicate glasses with good physical properties,chemical durability, and ion exchangeability have drawn attention foruse as cover glass. In particular, lithium containing aluminosilicateglasses, which have lower annealing and softening temperatures, lowercoefficient of thermal expansion (CTE) values, and fast ionexchangeability, are provided herein. Through different ion exchangeprocesses, greater central tension (CT), depth of compression (DOC), andhigh compressive stress (CS) can be achieved. However, the addition oflithium in the alkali aluminosilicate glass may reduce the meltingpoint, softening point, or liquidus viscosity of the glass.

Drawing processes for forming glass articles, such as, for example,glass sheets, are desirable because they allow a thin glass article tobe formed with few defects. It was previously thought that glasscompositions were required to have relatively high liquidusviscosities—such as a liquidus viscosity greater than 1000 kP, greaterthan 1100 kP, or greater than 1200 kP—to be formed by a drawing process,such as, for example, fusion drawing or slot drawing. However,developments in drawing processes allow glasses with lower liquidusviscosities to be used in drawing processes. Thus, glasses used indrawing processes may include more lithia than previously thought, andmay include more glass network forming components, such as, for example,SiO₂, Al₂O₃, B₂O₃, and P₂O₅. Accordingly, a balance of the various glasscomponents that allows the glass to realize the benefits of addinglithium and glass network formers to the glass composition, but thatdoes not negatively impact the glass composition are provided herein.

In embodiments of glass compositions described herein, the concentrationof constituent components (e.g., SiO₂, Al₂O₃, Li₂O, and the like) aregiven in mole percent (mol %) on an oxide basis, unless otherwisespecified. Components of the alkali aluminosilicate glass compositionaccording to embodiments are discussed individually below. It should beunderstood that any of the variously recited ranges of one component maybe individually combined with any of the variously recited ranges forany other component.

In embodiments of the alkali aluminosilicate glass compositionsdisclosed herein, SiO₂ is the largest constituent and, as such, SiO₂ isthe primary constituent of the glass network formed from the glasscomposition. Pure SiO₂ has a relatively low CTE and is alkali free.However, pure SiO₂ has a high melting point. Accordingly, if theconcentration of SiO₂ in the glass composition is too high, theformability of the glass composition may be diminished as higherconcentrations of SiO₂ increase the difficulty of melting the glass,which, in turn, adversely impacts the formability of the glass. Inembodiments, the glass composition generally comprises SiO₂ in an amountfrom greater than or equal to 55.0 mol % to less than or equal to 75.0mol %, and all ranges and sub-ranges between the foregoing values. Insome embodiments, the glass composition comprises SiO₂ in amountsgreater than or equal to 58.0 mol %, such as greater than or equal to60.0 mol %, greater than or equal to 62.0 mol %, greater than or equalto 64.0 mol %, greater than or equal to 66.0 mol %, greater than orequal to 68.0 mol %, or greater than or equal to 70.0 mol %. Inembodiments, the glass composition comprises SiO₂ in amounts less thanor equal to 72.0 mol %, such as less than or equal to 70.0 mol %, lessthan or equal to 68.0 mol %, less than or equal to 66.0 mol %, less thanor equal to 64.0 mol %, or less than or equal to 62.0 mol %. It shouldbe understood that, in embodiments, any of the above ranges may becombined with any other range. In embodiments, the glass compositioncomprises SiO₂ in an amount from greater than or equal to 58.0 mol % toless than or equal to 70.0 mol %, such as from greater than or equal to60.0 mol % to less than or equal to 68.0 mol %, or from greater than orequal to 62.0 mol % to less than or equal to 64.0 mol %, and all rangesand sub-ranges between the foregoing values.

The glass composition of embodiments may further comprise Al₂O₃. Al₂O₃may serve as a glass network former, similar to SiO₂. Al₂O₃ may increasethe viscosity of the glass composition due to its tetrahedralcoordination in a glass melt formed from a glass composition, decreasingthe formability of the glass composition when the amount of Al₂O₃ is toohigh. However, when the concentration of Al₂O₃ is balanced against theconcentration of SiO₂ and the concentration of alkali oxides in theglass composition, Al₂O₃ can reduce the liquidus temperature of theglass melt, thereby enhancing the liquidus viscosity and improving thecompatibility of the glass composition with certain forming processes,such as the fusion forming process. In embodiments, the glasscomposition generally comprises Al₂O₃ in a concentration of from greaterthan or equal to 8.0 mol % to less than or equal to 20.0 mol %, and allranges and sub-ranges between the foregoing values. In some embodiments,the glass composition comprises Al₂O₃ in amounts greater than or equalto 10.0 mol %, such as greater than or equal to 12.0 mol %, greater thanor equal to 14.0 mol %, greater than or equal to 16.0 mol %, greaterthan or equal to 17.0 mol %, or greater than or equal to 19.0 mol %. Inembodiments, the glass composition comprises Al₂O₃ in amounts less thanor equal to 19.0 mol %, such as less than or equal to 18.0 mol %, lessthan or equal to 17.0 mol %, less than or equal to 16.0 mol %, less thanor equal to 15.0 mol %, less than or equal to 14.0 mol %, or less thanor equal to 13.0 mol %. It should be understood that, in embodiments,any of the above ranges may be combined with any other range. Inembodiments, the glass composition comprises Al₂O₃ in an amount fromgreater than or equal to 10.0 mol % to less than or equal to 18.0 mol %,such as from greater than or equal to 12.0 mol % to less than or equalto 16.0 mol %, or from greater than or equal to 15.0 mol % to less thanor equal to 17.0 mol %, and all ranges and sub-ranges between theforegoing values.

Like SiO₂ and Al₂O₃, P₂O₅ may be added to the glass composition as anetwork former, thereby reducing the meltability and formability of theglass composition. Thus, P₂O₅ may be added in amounts that do not overlydecrease these properties. The addition of P₂O₅ may also increase thediffusivity of ions in the glass composition during ion exchangetreatment, thereby increasing the efficiency of these treatments. Inembodiments, the glass composition may comprise P₂O₅ in amounts fromgreater than or equal to 0.0 mol % to less than or equal to 8.0 mol %,and all ranges and sub-ranges between the foregoing values. In someembodiments, the glass composition may comprise P₂O₅ in amounts greaterthan or equal to 0.5 mol %, greater than or equal to 1.0 mol %, greaterthan or equal to 1.5 mol %, greater than or equal to 2.0 mol %, greaterthan or equal to 2.5 mol %, greater than or equal to 3.0 mol %, greaterthan or equal to 3.5 mol %, greater than or equal to 4.0 mol %, orgreater than or equal to 4.5 mol %. In embodiments, the glasscomposition may comprise P₂O₅ in an amount less than or equal to 7.5 mol%, less than or equal to 7.0 mol %, less than or equal to 6.5 mol %,less than or equal to 6.0 mol %, less than or equal to 5.5 mol %, lessthan or equal to 5.0 mol %, less than or equal to 4.5 mol %, less thanor equal to 4.0 mol %, less than or equal to 3.5 mol %, less than orequal to 3.0 mol %, less than or equal to 2.5 mol %, less than or equalto 2.0 mol %, less than or equal to 1.5 mol %, less than or equal to 1.0mol %, or less than or equal to 0.5 mol %. It should be understood that,in embodiments, any of the above ranges may be combined with any otherrange. In embodiments, the glass composition may comprise P₂O₅ inamounts from greater than or equal to 0.5 mol % to less than or equal to7.5 mol %, from greater than or equal to 1.0 mol % to less than or equalto 7.0 mol %, from greater than or equal to 1.5 mol % to less than orequal to 6.5 mol %, from greater than or equal to 2.0 mol % to less thanor equal to 6.0 mol %, from greater than or equal to 2.5 mol % to lessthan or equal to 5.5 mol %, or from greater than or equal to 3.0 mol %to less than or equal to 5.0 mol %, and all ranges and sub-rangesbetween the foregoing values.

Like SiO₂, Al₂O₃, and P₂O₅, B₂O₃ may be added to the glass compositionas a network former, thereby reducing the meltability and formability ofthe glass composition. Thus, B₂O₃ may be added in amounts that do notoverly decrease these properties. In embodiments, the glass compositionmay comprise B₂O₃ in amounts from greater than or equal to 0.0 mol %B₂O₃ to less than or equal to 3.0 mol % B₂O₃, and all ranges andsub-ranges between the foregoing values. In some embodiments, the glasscomposition may comprise B₂O₃ in amounts greater than or equal to 0.5mol %, greater than or equal to 1.0 mol %, greater than or equal to 1.5mol %, greater than or equal to 2.0 mol %, or greater than or equal to2.5 mol %. In embodiments, the glass composition may comprise B₂O₃ in anamount less than or equal to 2.5 mol %, less than or equal to 2.0 mol %,less than or equal to 1.5 mol %, less than or equal to 1.0 mol %, orless than or equal to 0.5 mol %. It should be understood that, inembodiments, any of the above ranges may be combined with any otherrange. In embodiments, the glass composition comprises B₂O₃ in amountsfrom greater than or equal to 0.5 mol % to less than or equal to 2.5 mol%, or from greater than or equal to 1.0 mol % to less than or equal to2.0 mol %, and all ranges and sub-ranges between the foregoing values.

In some embodiments, the glass composition comprises at least one ofB₂O₃ and P₂O₅ as glass network forming elements. Accordingly, inembodiments B₂O₃+P₂O₅ is greater than 0.0 mol %, such as greater than orequal to 0.5 mol %, greater than or equal to 1.0 mol %, greater than orequal to 1.5 mol %, greater than or equal to 2.0 mol %, greater than orequal to 2.5 mol %, greater than or equal to 3.0 mol %, greater than orequal to 3.5 mol %, greater than or equal to 4.0 mol %, greater than orequal to 4.5 mol %, greater than or equal to 5.0 mol %, greater than orequal to 5.5 mol %, greater than or equal to 6.0 mol %, greater than orequal to 6.5 mol %, greater than or equal to 7.0 mol %, greater than orequal to 7.5 mol %, or greater than or equal to 8.0 mol %, and allranges and sub-ranges between the foregoing values. In embodiments,B₂O₃+P₂O₅ is less than or equal to 7.5 mol %, such as less than or equalto 7.0 mol %, less than or equal to 6.5 mol %, less than or equal to 6.0mol %, less than or equal to 5.5 mol %, less than or equal to 5.0 mol %,less than or equal to 4.5 mol %, less than or equal to 4.0 mol %, lessthan or equal to 3.5 mol %, less than or equal to 3.0 mol %, less thanor equal to 2.5 mol %, less than or equal to 2.0 mol %, less than orequal to 1.5 mol %, less than or equal to 1.0 mol %, or less than orequal to 0.5 mol %. It should be understood that, in embodiments, any ofthe above ranges may be combined with any other range. In embodiments,the glass composition comprises B₂O₃+P₂O₅ in amounts from greater thanor equal to 0.5 mol % to less than or equal to 7.5 mol %, greater thanor equal to 1.0 mol % to less than or equal to 7.0 mol %, greater thanor equal to 1.5 mol % to less than or equal to 6.5 mol %, greater thanor equal to 2.0 mol % to less than or equal to 6.0 mol %, greater thanor equal to 2.5 mol % to less than or equal to 5.5 mol %, or greaterthan or equal to 3.0 mol % to less than or equal to 5.0 mol %, and allranges and sub-ranges between the foregoing values.

The effects of Li₂O in the glass composition are discussed above anddiscussed in further detail below. In part, the addition of lithium inthe glass allows for better control of an ion exchange process andfurther reduces the softening point of the glass. In embodiments, theglass composition generally comprises Li₂O in an amount from greaterthan or equal to 3.0 mol % to less than or equal to 15.0 mol %, and allranges and sub-ranges between the foregoing values. In some embodiments,the glass composition comprises Li₂O in amounts greater than or equal to3.5 mol %, greater than or equal to 4.0 mol %, greater than or equal to4.5 mol %, greater than or equal to 5.0 mol %, greater than or equal to5.5 mol %, greater than or equal to 6.0 mol %, greater than or equal to6.5 mol %, greater than or equal to 7.0 mol %, greater than or equal to7.5 mol %, greater than or equal to 8.0 mol %, greater than or equal to8.5 mol %, greater than or equal to 9.0 mol %, greater than or equal to9.5 mol %, greater than or equal to 10.0 mol %, greater than or equal to10.5 mol %, greater than or equal to 11.0 mol %, greater than or equalto 11.5 mol %, greater than or equal to 12.0 mol %, greater than orequal to 12.5 mol %, greater than or equal to 13.0 mol %, greater thanor equal to 13.5 mol %, greater than or equal to 14.0 mol %, or greaterthan or equal to 14.5 mol %. In some embodiments, the glass compositioncomprises Li₂O in amounts less than or equal to 14.5 mol %, less than orequal to 14.0 mol %, less than or equal to 13.5 mol %, less than orequal to 13.0 mol %, less than or equal to 12.5 mol %, less than orequal to 12.0 mol %, less than or equal to 11.5 mol %, less than orequal to 11.0 mol %, less than or equal to 10.5 mol %, less than orequal to 10.0 mol %, less than or equal to 9.5 mol %, less than or equalto 9.0 mol %, less than or equal to 8.5 mol %, less than or equal to 8.0mol %, less than or equal to 7.5 mol %, less than or equal to 7.0 mol %,less than or equal to 6.5 mol %, less than or equal to 6.0 mol %, lessthan or equal to 5.5 mol %, less than or equal to 5.0 mol %, less thanor equal to 4.5 mol %, less than or equal to 4.0 mol %, or less than orequal to 3.5 mol %. It should be understood that, in embodiments, any ofthe above ranges may be combined with any other range. In embodiments,the glass composition comprises Li₂O in an amount from greater than orequal to 3.5 mol % to less than or equal to 14.5 mol %, such as fromgreater than or equal to 4.0 mol % to less than or equal to 14.0 mol %,from greater than or equal to 4.5 mol % to less than or equal to 13.5mol %, from greater than or equal to 5.0 mol % to less than or equal to13.0 mol %, from greater than or equal to 5.5 mol % to less than orequal to 12.5 mol %, from greater than or equal to 6.0 mol % to lessthan or equal to 12.0 mol %, from greater than or equal to 6.5 mol % toless than or equal to 11.5 mol %, or from greater than or equal to 7.0mol % to less than or equal to 10.0 mol %, and all ranges and sub-rangesbetween the foregoing values.

In addition to being a glass network forming component, Al₂O₃ also aidsin increasing the ion exchangeability of the glass composition.Therefore, in embodiments, the amount of Al₂O₃ and other components thatmay be ion exchanged may be relatively high. For example, Li₂O is an ionexchangeable component. In some embodiments, the amount of Al₂O₃+Li₂O inthe glass composition may be greater than 22.5 mol %, such as greaterthan or equal to 23.0 mol %, greater than or equal to 23.5 mol %,greater than or equal to 24.0 mol %, greater than or equal to 24.5 mol%, greater than or equal to 25.0 mol %, greater than or equal to 25.5mol %, or greater than or equal to 26.0 mol %, and all ranges andsub-ranges between the foregoing values. In some embodiments, the amountof Al₂O₃+Li₂O is less than or equal to 26.5 mol %, such as less than orequal to 26.0 mol %, less than or equal to 25.5 mol %, less than orequal to 25.0 mol %, less than or equal to 24.5 mol %, less than orequal to 24.0 mol %, less than or equal to 23.5 mol %, or less than orequal to 23.0 mol %, and all ranges and sub-ranges between the foregoingvalues. It should be understood that, in embodiments, any of the aboveranges may be combined with any other range. In embodiments, the amountof Al₂O₃+Li₂O is from greater than or equal to 23.0 mol % to less thanor equal to 26.5 mol %, from greater than or equal to 23.5 mol % to lessthan or equal to 26.0 mol %, from greater than or equal to 24.0 mol % toless than or equal to 25.5 mol %, or from greater than or equal to 24.5mol % to less than or equal to 25.0 mol %, and all ranges and sub-rangesbetween the foregoing values.

According to embodiments, the glass composition may also comprise alkalimetal oxides other than Li₂O, such as Na₂O. Na₂O aids in the ionexchangeability of the glass composition, and also increases the meltingpoint of the glass composition and improves formability of the glasscomposition. However, if too much Na₂O is added to the glasscomposition, the CTE may be too low, and the melting point may be toohigh. In embodiments, the glass composition generally comprises Na₂O inan amount from greater than 5.0 mol % Na₂O to less than or equal to 15mol % Na₂O, and all ranges and sub-ranges between the foregoing values.In some embodiments, the glass composition comprises Na₂O in amountsgreater than or equal to 5.5 mol %, greater than or equal to 6.0 mol %,greater than or equal to 6.5 mol %, greater than or equal to 7.0 mol %,greater than or equal to 7.5 mol %, greater than or equal to 8.0 mol %,greater than or equal to 8.5 mol %, greater than or equal to 9.0 mol %,greater than or equal to 9.5 mol %, greater than or equal to 10.0 mol %,greater than or equal to 10.5 mol %, greater than or equal to 11.0 mol%, greater than or equal to 11.5 mol %, greater than or equal to 12.0mol %, greater than or equal to 12.5 mol %, greater than or equal to13.0 mol %, greater than or equal to 13.5 mol %, greater than or equalto 14.0 mol %, or greater than or equal to 14.5 mol %. In someembodiments, the glass composition comprises Na₂O in amounts less thanor equal to 14.5 mol %, less than or equal to 14.0 mol %, less than orequal to 13.5 mol %, less than or equal to 13.0 mol %, less than orequal to 12.5 mol %, less than or equal to 12.0 mol %, less than orequal to 11.5 mol %, less than or equal to 11.0 mol %, less than orequal to 10.5 mol %, less than or equal to 10.0 mol %, less than orequal to 9.5 mol %, less than or equal to 9.0 mol %, less than or equalto 8.5 mol %, less than or equal to 8.0 mol %, less than or equal to 7.5mol %, less than or equal to 7.0 mol %, less than or equal to 6.5 mol %,less than or equal to 6.0 mol %, less than or equal to 5.5 mol %, lessthan or equal to 5.0 mol %, or less than or equal to 4.5 mol %. Itshould be understood that, in embodiments, any of the above ranges maybe combined with any other range. In embodiments, the glass compositioncomprises Na₂O in an amount from greater than or equal to 5.5 mol % toless than or equal to 14.5 mol %, such as from greater than or equal to6.0 mol % to less than or equal to 14.0 mol %, from greater than orequal to 6.5 mol % to less than or equal to 13.5 mol %, from greaterthan or equal to 7.0 mol % to less than or equal to 13.0 mol %, fromgreater than or equal to 7.5 mol % to less than or equal to 12.5 mol %,from greater than or equal to 8.0 mol % to less than or equal to 12.0mol %, from greater than or equal to 8.5 mol % to less than or equal to11.5 mol %, or from greater than or equal to 9.0 mol % to less than orequal to 10.0 mol %, and all ranges and sub-ranges between the foregoingvalues.

As noted above, Al₂O₃ aids in increasing the ion exchangeability of theglass composition. Therefore, in embodiments, the amount of Al₂O₃ andother components that may be ion exchanged may be relatively high. Forexample, Li₂O and Na₂O are ion exchangeable components. In someembodiments, the amount of Al₂O₃+Li₂O+Na₂O in the glass composition maybe greater than 25.0 mol %, such as greater than or equal to 25.5 mol %,greater than or equal to 26.0 mol %, greater than or equal to 26.5 mol%, greater than or equal to 27.0 mol %, greater than or equal to 27.5mol %, greater than or equal to 28.0 mol %, greater than or equal to28.5 mol %, greater than or equal to 29.0 mol %, or greater than orequal to 29.5 mol %, and all ranges and sub-ranges between the foregoingvalues. In some embodiments, the amount of Al₂O₃+Li₂O+Na₂O is less thanor equal to 30.0 mol %, such as less than or equal to 29.5 mol %, lessthan or equal to 29.0 mol %, less than or equal to 28.5 mol %, less thanor equal to 28.0 mol %, less than or equal to 27.5 mol %, less than orequal to 27.0 mol %, less than or equal to 26.5 mol %, less than orequal to 26.0 mol %, or less than or equal to 25.5 mol %, and all rangesand sub-ranges between the foregoing values. It should be understoodthat, in embodiments, any of the above ranges may be combined with anyother range. In embodiments, the amount of Al₂O₃+Li₂O+Na₂O is fromgreater than or equal to 25.0 mol % to less than or equal to 30.0 mol %,from greater than or equal to 25.5 mol % to less than or equal to 29.5mol %, from greater than or equal to 26.0 mol % to less than or equal to29.0 mol %, from greater than or equal to 26.5 mol % to less than orequal to 28.5 mol %, or from greater than or equal to 27.0 mol % to lessthan or equal to 28.0 mol %, and all ranges and sub-ranges between theforegoing values.

Like Na₂O, K₂O also promotes ion exchange and increases the DOC of acompressive stress layer. However, adding K₂O may cause the CTE to betoo low, and the melting point to be too high. In embodiments, the glasscomposition comprises less than or equal to 1.5 mol % K₂O, such as lessthan or equal to 1.0 mol %, or less than or equal to 0.5 mol %, and allranges and sub-ranges between the foregoing values. In some embodiments,the glass composition is substantially free or free of potassium. Asused herein, the term “substantially free” means that the component isnot added as a component of the batch material even though the componentmay be present in the final glass in very small amounts as acontaminant, such as less than 0.01 mol %.

MgO lowers the viscosity of a glass, which enhances the formability, thestrain point and the Young's modulus, and may improve the ion exchangeability. However, when too much MgO is added to the glass composition,the density and the CTE of the glass composition increase. Inembodiments, the glass composition generally comprises MgO in aconcentration of from greater than or equal to 0.0 mol % to less than orequal to 4.0 mol %, and all ranges and sub-ranges between the foregoingvalues. In some embodiments, the glass composition comprises MgO inamounts greater than or equal to 0.2 mol %, greater than or equal to 0.5mol %, greater than or equal to 1.0 mol %, greater than or equal to 1.5mol %, greater than or equal to 2.0 mol %, greater than or equal to 2.5mol %, greater than or equal to 3.0 mol %, or greater than or equal to3.5 mol %. In some embodiments, the glass composition comprises MgO inamounts less than or equal to 3.5 mol %, less than or equal to 3.0 mol%, less than or equal to 2.5 mol %, less than or equal to 2.0 mol %,less than or equal to 1.5 mol %, less than or equal to 1.0 mol %, lessthan or equal to 0.5 mol %, less than or equal to 0.4 mol %, or lessthan or equal to 0.2 mol %. It should be understood that, inembodiments, any of the above ranges may be combined with any otherrange. In embodiments, the glass composition comprises MgO in an amountfrom greater than or equal to 0.2 mol % to less than or equal to 3.5 mol%, such as from greater than or equal to 0.5 mol % to less than or equalto 3.0 mol %, from greater than or equal to 1.0 mol % to less than orequal to 2.5 mol %, or from greater than or equal to 1.5 mol % to lessthan or equal to 2.0 mol %, and all ranges and sub-ranges between theforegoing values.

CaO lowers the viscosity of a glass, which enhances the formability, thestrain point and the Young's modulus, and may improve the ion exchangeability. However, when too much CaO is added to the glass composition,the density and the CTE of the glass composition increase. Inembodiments, the glass composition generally comprises CaO in aconcentration of from greater than or equal to 0.0 mol % to less than orequal to 2.0 mol %, and all ranges and sub-ranges between the foregoingvalues. In some embodiments, the glass composition comprises CaO inamounts greater than or equal to 0.2 mol %, greater than or equal to 0.4mol %, greater than or equal to 0.6 mol %, greater than or equal to 0.8mol %, greater than or equal to 1.0 mol %, greater than or equal to 1.2mol %, greater than or equal to 1.4 mol %, greater than or equal to 1.6mol %, or greater than or equal to 1.8 mol %. In some embodiments, theglass composition comprises CaO in amounts less than or equal to 1.8 mol%, less than or equal to 1.6 mol %, less than or equal to 1.4 mol %,less than or equal to 1.2 mol %, less than or equal to 1.0 mol %, lessthan or equal to 0.8 mol %, less than or equal to 0.6 mol %, less thanor equal to 0.4 mol %, or less than or equal to 0.2 mol %. It should beunderstood that, in embodiments, any of the above ranges may be combinedwith any other range. In embodiments, the glass composition comprisesCaO in an amount from greater than or equal to 0.2 mol % to less than orequal to 1.8 mol %, such as from greater than or equal to 0.4 mol % toless than or equal to 1.6 mol %, from greater than or equal to 0.6 mol %to less than or equal to 1.4 mol %, or from greater than or equal to 0.8mol % to less than or equal to 1.2 mol %, and all ranges and sub-rangesbetween the foregoing values.

In embodiments, the glass composition may optionally include one or morefining agents. In some embodiments, the fining agents may include, forexample, SnO₂. In such embodiments, SnO₂ may be present in the glasscomposition in an amount less than or equal to 0.2 mol %, such as fromgreater than or equal to 0.0 mol % to less than or equal to 0.1 mol %,and all ranges and sub-ranges between the foregoing values. Inembodiments, SnO₂ may be present in the glass composition in an amountfrom greater than or equal to 0.0 mol % to less than or equal to 0.2 mol%, or greater than or equal to 0.1 mol % to less than or equal to 0.2mol %, and all ranges and sub-ranges between the foregoing values. Insome embodiments, the glass composition may be substantially free orfree of SnO₂.

ZnO enhances the ion exchange performance of a glass, such as byincreasing the compressive stress of the glass. However, adding too muchZnO may increase density and cause phase separation. In embodiments, theglass composition may comprise ZnO in amounts from greater than or equalto 0.0 mol % to less than or equal to 2.5 mol %, such as from greaterthan or equal to 0.2 mol % to less than or equal to 2.0 mol %, or fromgreater than or equal to 0.5 mol % to less than or equal to 1.5 mol %,and all ranges and sub-ranges between the foregoing values. In someembodiments, the glass composition may comprise ZnO in amounts greaterthan or equal to 0.3 mol %, greater than or equal to 0.5 mol %, orgreater than or equal to 0.8 mol %. In embodiments, the glasscomposition may comprise ZnO in amounts less than or equal to 2.0 mol %,such as less than or equal to 1.5 mol %, or less than or equal to 1.0mol %. It should be understood that, in embodiments, any of the aboveranges may be combined with any other range.

In addition to the above individual components, glass compositionsaccording to embodiments disclosed herein may comprise divalent cationoxides (referred to herein as RO) in amounts from greater than or equalto 0.0 mol % to less than or equal to 5.0 mol %, and all ranges andsub-ranges between the foregoing values. As used herein, divalent cationoxides (RO) include, but are not limited to, MgO, CaO, SrO, BaO, FeO,and ZnO. In some embodiments, the glass composition may comprise RO inan amount greater than or equal to 0.2 mol %, such as greater than orequal to 0.5 mol %, greater than or equal to 1.0 mol %, greater than orequal to 1.5 mol %, greater than or equal to 2.0 mol %, greater than orequal to 2.5 mol %, greater than or equal to 3.0 mol %, greater than orequal to 3.5 mol %, greater than or equal to 4.0 mol %, or greater thanor equal to 4.5 mol %. In embodiments, the glass composition maycomprise RO in an amount less than or equal to 4.5 mol %, such as lessthan or equal to 4.0 mol %, less than or equal to 3.5 mol %, less thanor equal to 3.0 mol %, less than or equal to 2.5 mol %, less than orequal to 2.0 mol %, less than or equal to 1.5 mol %, less than or equalto 1.0 mol %, or less than or equal to 0.5 mol %. It should beunderstood that, in embodiments, any of the above ranges may be combinedwith any other range. In embodiments, the glass composition may compriseRO in amounts from greater than or equal to 0.2 mol % to less than orequal to 4.5 mol %, such as greater than or equal to 0.5 mol % to lessthan or equal to 4.0 mol %, greater than or equal to 1.0 mol % to lessthan or equal to 3.5 mol %, greater than or equal to 1.5 mol % to lessthan or equal to 3.0 mol %, or greater than or equal to 2.0 mol % toless than or equal to 2.5 mol %, and all ranges and sub-ranges betweenthe foregoing values.

The amount of alkali metal oxides (also referred to herein as “R₂O”) andRO in the glass composition may have an effect on the viscosity of theglass composition, namely the softening point is decreased withincreasing R₂O+RO content to enable easier 3 D forming processes. Asutilized herein, R₂O includes Li₂O, Na₂O, K₂O, Rb₂O, Cs₂O, and Fr₂O. Inembodiments, the sum of R₂O and RO (i.e., R₂O+RO) is greater than orequal to 18.0 mol %, such as greater than or equal to 18.5 mol %,greater than or equal to 19.0 mol %, greater than or equal to 19.5 mol%, greater than or equal to 20.0 mol %, greater than or equal to 20.5mol %, greater than or equal to 21.0 mol %, greater than or equal to21.5 mol %, greater than or equal to 22.0 mol %, greater than or equalto 22.5 mol %, or greater than or equal to 23.0 mol %. In embodiments,the sum of R₂O and RO is less than or equal to 22.5 mol %, such as lessthan or equal to 22.0 mol %, less than or equal to 21.5 mol %, less thanor equal to 21.0 mol %, less than or equal to 20.5 mol %, less than orequal to 20.0 mol %, less than or equal to 19.5 mol %, less than orequal to 19.0 mol %, or less than or equal to 18.5 mol %. It should beunderstood that, in embodiments, any of the above ranges may be combinedwith any other range. In embodiments, the sum of R₂O and RO in the glasscomposition is from greater than or equal to 18.0 mol % to less than orequal to 23.0 mol %, such as from greater than or equal to 18.5 mol % toless than or equal to 22.5 mol %, from greater than or equal to 19.0 mol% to less than or equal to 22.0 mol %, from greater than or equal to19.5 mol % to less than or equal to 21.5 mol %, or from greater than orequal to 20.0 mol % to less than or equal to 21.0 mol %, and all rangesand sub-ranges between the foregoing values.

In embodiments, a relationship, in mol %, of R₂O/Al₂O₃ is greater thanor equal to 1.06. Having a ratio of R₂O to Al₂O₃ above 1.06 improves themeltability of the glass. One skilled in the art of glassmaking knowsthat R₂O in excess of Al₂O₃ greatly improves the dissolution of SiO₂ ina glass melt. This value is closely controlled in glass design toimprove yields by reducing losses due to inclusions such as silicaknots. In some embodiments, the molar ratio of R₂O/Al₂O₃ is greater thanor equal to 1.10, such as greater than or equal to 1.20, greater than orequal to 1.30, greater than or equal to 1.40, greater than or equal to1.50, greater than or equal to 1.60, greater than or equal to 1.70,greater than or equal to 1.80, greater than or equal to 1.90, or greaterthan or equal to 2.00. However, if the R₂O/Al₂O₃ ratio is too high, theglass may become susceptible to degradation. In embodiments, a molarratio of R₂O/Al₂O₃ is less than or equal to 2.10, such as less than orequal to 2.00, less than or equal to 1.90, less than or equal to 1.80,less than or equal to 1.70, less than or equal to 1.60, less than orequal to 1.50, less than or equal to 1.40, less than or equal to 1.30,less than or equal to 1.20, or less than or equal to 1.10. It should beunderstood that, in embodiments, any of the above ranges may be combinedwith any other range. In embodiments, the molar ratio of R₂O/Al₂O₃ isfrom greater than or equal to 1.06 to less than or equal to 2.10, suchas from greater than or equal to 1.10 to less than or equal to 1.90,from greater than or equal to 1.20 to less than or equal to 1.80, orfrom greater than or equal to 1.30 to less than or equal to 1.70, andall ranges and sub-ranges between the foregoing values.

In embodiments, the total amount of network forming components (e.g.,Al₂O₃+SiO₂+B₂O₃+P₂O₅) is greater than or equal to 78.0 mol %, such asgreater than or equal to 78.5 mol %, greater than or equal to 79.0 mol%, greater than or equal to 78.5 mol %, greater than or equal to 80.0mol %, greater than or equal to 80.5 mol %, greater than or equal to81.0 mol %, greater than or equal to 81.5 mol %, greater than or equalto 82.0 mol %, greater than or equal to 82.5 mol %, greater than orequal to 83.0 mol %, greater than or equal to 83.5 mol %, or greaterthan or equal to 84.0 mol %. Having a high amount of network formingcomponents increases the connectivity and free volume of the glass,which makes it less brittle and improves the damage resistance. Inembodiments, the total amount of network forming components is less thanor equal to 85.0 mol %, such as less than or equal to 84.5 mol %, lessthan or equal to 84.0 mol %, less than or equal to 83.5 mol %, less thanor equal to 83.0 mol %, less than or equal to 82.5 mol %, less than orequal to 82.0 mol %, less than or equal to 81.5 mol %, less than orequal to 81.0 mol %, less than or equal to 80.5 mol %, less than orequal to 80.0 mol %, less than or equal to 79.5 mol %, or less than orequal to 79.0 mol %. It should be understood that, in embodiments, anyof the above ranges may be combined with any other range. Inembodiments, the total amount of network forming components is fromgreater than or equal to 78.0 mol % to less than or equal to 85.0 mol %,such as greater than or equal to 78.0 mol % to less than or equal to83.0 mol %, greater than or equal to 80.0 mol % to less than or equal to82.0 mol %, or greater than or equal to 80.5 mol % to less than or equalto 81.5 mol %, and all ranges and sub-ranges between the foregoingvalues.

In one or more embodiments, the amount of glass network formingcomponents, such as SiO₂, Al₂O₃, B₂O₃, and P₂O₅, may be balanced againstthe amount of Li₂O in the glass composition. Without being bound to anyparticular theory, it is believed that Li₂O decreases the free volume inthe glass relative to other alkali ions, thus reducing the indentationcrack resistance. Since Li₂O is needed for Na⁺ for Li⁺, ion-exchange,the free volume reducing Li₂O should be managed relative to the freevolume increasing network formers, i.e. SiO₂, Al₂O₃, B₂O₃, and P₂O₅ toretain suitable sharp contact damage resistance. Thus, in embodiments,the ratio, in mol %, of glass network formers to Li₂O (i.e.,(SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O) is greater than or equal to 8.0, such asgreater than or equal to 8.5, greater than or equal to 9.0, greater thanor equal to 9.5, greater than or equal to 10.0, greater than or equal to10.5, greater than or equal to 11.0, greater than or equal to 11.5,greater than or equal to 12.0, greater than or equal to 12.5, greaterthan or equal to 13.0, greater than or equal to 13.5, greater than orequal to 14.0, greater than or equal to 14.5, greater than or equal to15.0, greater than or equal to 15.5, greater than or equal to 16.0, orgreater than or equal to 16.5. In other embodiments the ratio(SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O is less than or equal to 17.0, such as lessthan or equal to 16.5, less than or equal to 16.0, less than or equal to15.5, less than or equal to 15.0, less than or equal to 14.5, less thanor equal to 14.0, less than or equal to 13.5, less than or equal to13.0, less than or equal to 12.5, less than or equal to 12.0, less thanor equal to 11.5, less than or equal to 11.0, less than or equal to10.5, less than or equal to 10.0, less than or equal to 9.5, less thanor equal to 9.0, or less than or equal to 8.5. It should be understoodthat, in embodiments, any of the above ranges may be combined with anyother range. In embodiments, the ratio (SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O isfrom greater than or equal to 8.0 to less than or equal to 17.0, such asfrom greater than or equal to 9.0 to less than or equal to 16.0, fromgreater than or equal to 10.0 to less than or equal to 15.0, fromgreater than or equal to 11.0 to less than or equal to 14.0, or fromgreater than or equal to 12.0 to less than or equal to 13.0, and allranges and sub-ranges between the foregoing values.

The sum of Al₂O₃+Li₂O should be greater than or equal to 23.0 mol %,such as greater than or equal to 23.5 mol %, greater than or equal to24.0 mol %, greater than or equal to 24.5 mol %, greater than or equalto 25.0 mol %, greater than or equal to 25.5 mol %, greater than orequal to 26.0 mol %, greater than or equal to 26.5 mol %, greater thanor equal to 27.0 mol %, greater than or equal to 27.5 mol %, greaterthan or equal to 28.0 mol %, greater than or equal to 28.5 mol %,greater than or equal to 29.0 mol %, greater than or equal to 29.5 mol%, or greater than or equal to 30.0 mol %. The sum of Al₂O₃+Li₂O shouldbe as high as possible to promote maximum compressive stress at a givendepth for the tail of the ion-exchange profile.

In embodiments, the glass article may be substantially free of one orboth of arsenic and antimony. In other embodiments, the glass articlemay be free of one or both of arsenic and antimony.

Physical properties of the alkali aluminosilicate glass compositions asdisclosed above will now be discussed. These physical properties can beachieved by modifying the component amounts of the alkalialuminosilicate glass composition, as will be discussed in more detailwith reference to the examples.

Glass compositions according to embodiments may have a density fromgreater than or equal to 2.20 g/cm³ to less than or equal to 2.60 g/cm³,such as from greater than or equal to 2.25 g/cm³ to less than or equalto 2.60 g/cm³, from greater than or equal to 2.30 g/cm³ to less than orequal to 2.60 g/cm³, from greater than or equal to 2.35 g/cm³ to lessthan or equal to 2.60 g/cm³, from greater than or equal to 2.40 g/cm³ toless than or equal to 2.60 g/cm³, or from greater than or equal to 2.45g/cm³ to less than or equal to 2.60 g/cm³. In embodiments, the glasscomposition may have a density from greater than or equal to 2.20 g/cm³to less than or equal to 2.45 g/cm³, such as from greater than or equalto 2.20 g/cm³ to less than or equal to 2.40 g/cm³, from greater than orequal to 2.20 g/cm³ to less than or equal to 2.35 g/cm³, from greaterthan or equal to 2.20 g/cm³ to less than or equal to 2.30 g/cm³, or fromgreater than or equal to 2.20 g/cm³ to less than or equal to 2.25 g/cm³,and all ranges and sub-ranges between the foregoing values. Generally,as larger, denser alkali metal cations, such as Na⁺ or K⁺, are replacedwith smaller alkali metal cations, such as Li⁺, in an alkalialuminosilicate glass composition, the density of the glass compositiondecreases. Accordingly, the higher the amount of lithium in the glasscomposition, the less dense the glass composition will be. The densityvalues recited in this disclosure refer to a value as measured by thebuoyancy method of ASTM C693-93(2013).

In embodiments, the liquidus viscosity of the glass composition is lessthan or equal to 1000 kP, such as less than or equal to 800 kP, lessthan or equal to 600 kP, less than or equal to 400 kP, less than orequal to 200 kP, less than or equal to 100 kP, less than or equal to 75kP, less than or equal to 60 kP, less than or equal to 50 kP, less thanor equal to 40 kP, or less than or equal to 30 kP. In embodiments, theliquidus viscosity of the glass composition is greater than or equal to20 kP, such as greater than or equal to 40 kP, greater than or equal to60 kP, greater than or equal to 80 kP, greater than or equal to 100 kP,greater than or equal to 120 kP, greater than or equal to 140 kP, orgreater than or equal to 160 kP. It should be understood that, inembodiments, any of the above ranges may be combined with any otherrange. In embodiments, the liquidus viscosity of the glass compositionis from greater than or equal to 20 kP to less than or equal to 1000 kP,such as greater than or equal to 40 kP to less than or equal to 900 kP,greater than or equal to 60 kP to less than or equal to 800 kP, orgreater than or equal to 80 kP to less than or equal to 700 kP, and allranges and sub-ranges between the foregoing values. The liquidusviscosity is determined by the following method. First, the liquidustemperature of the glass is measured in accordance with ASTM C829-81(2015), titled “Standard Practice for Measurement of LiquidusTemperature of Glass by the Gradient Furnace Method”. Next, theviscosity of the glass at the liquidus temperature is measured inaccordance with ASTM C965-96(2012), titled “Standard Practice forMeasuring Viscosity of Glass Above the Softening Point”.

The addition of lithium to the glass composition also affects theYoung's modulus, shear modulus, and Poisson's ratio of the glasscomposition. In embodiments, the Young's modulus of the glasscomposition may be from greater than or equal to 65 GPa to less than orequal to 85 GPa, such as from greater than or equal to 67 GPa to lessthan or equal to 82 GPa, from greater than or equal to 70 GPa to lessthan or equal to 80 GPa, from greater than or equal to 72 GPa to lessthan or equal to 78 GPa, or from greater than or equal to 74 GPa to lessthan or equal to 76 GPa, and all ranges and sub-ranges between theforegoing values. In other embodiments, the Young's modulus of the glasscomposition may be from greater than or equal to 66 GPa to less than orequal to 85 GPa, such as from greater than or equal to 68 GPa to lessthan or equal to 85 GPa, from greater than or equal to 70 GPa to lessthan or equal to 85 GPa, from greater than or equal to 72 GPa to lessthan or equal to 85 GPa, from greater than or equal to 74 GPa to lessthan or equal to 85 GPa, from greater than or equal to 76 GPa to lessthan or equal to 85 GPa, from greater than or equal to 78 GPa to lessthan or equal to 85 GPa, from greater than or equal to 80 GPa to lessthan or equal to 85 GPa, or from greater than or equal to 82 GPa to lessthan or equal to 85 GPa, and all ranges and sub-ranges between theforegoing values. In embodiments, the Young's modulus may be fromgreater than or equal to 65 GPa to less than or equal to 84 GPa, such asfrom greater than or equal to 65 GPa to less than or equal to 82 GPa,from greater than or equal to 65 GPa to less than or equal to 80 GPa,from greater than or equal to 65 GPa to less than or equal to 78 GPa,from greater than or equal to 65 GPa to less than or equal to 76 GPa,from greater than or equal to 65 GPa to less than or equal to 74 GPa,from greater than or equal to 65 GPa to less than or equal to 72 GPa,from greater than or equal to 65 GPa to less than or equal to 70 GPa,from greater than or equal to 65 GPa to less than or equal to 68 GPa, orfrom greater than or equal to 65 GPa to less than or equal to 10 GPa,and all ranges and sub-ranges between the foregoing values. The Young'smodulus values recited in this disclosure refer to a value as measuredby a resonant ultrasonic spectroscopy technique of the general type setforth in ASTM E2001-13, titled “Standard Guide for Resonant UltrasoundSpectroscopy for Defect Detection in Both Metallic and Non-metallicParts.”

The softening point of the glass composition is affected by the additionof lithium to the glass composition. According to one or moreembodiments, the softening point of the glass composition may be fromgreater than or equal to 700° C. to less than or equal to 930° C., suchas from greater than or equal to 705° C. to less than or equal to 925°C., from greater than or equal to 710° C. to less than or equal to 920°C., from greater than or equal to 715° C. to less than or equal to 915°C., from greater than or equal to 720° C. to less than or equal to 910°C., from greater than or equal to 725° C. to less than or equal to 905°C., from greater than or equal to 730° C. to less than or equal to 900°C., from greater than or equal to 735° C. to less than or equal to 895°C., from greater than or equal to 740° C. to less than or equal to 890°C., from greater than or equal to 745° C. to less than or equal to 885°C., from greater than or equal to 750° C. to less than or equal to 880°C., from greater than or equal to 755° C. to less than or equal to 875°C., from greater than or equal to 760° C. to less than or equal to 870°C., from greater than or equal to 765° C. to less than or equal to 865°C., from greater than or equal to 770° C. to less than or equal to 860°C., from greater than or equal to 775° C. to less than or equal to 855°C., from greater than or equal to 780° C. to less than or equal to 850°C., from greater than or equal to 785° C. to less than or equal to 845°C., from greater than or equal to 790° C. to less than or equal to 840°C., from greater than or equal to 795° C. to less than or equal to 835°C., from greater than or equal to 800° C. to less than or equal to 830°C., from greater than or equal to 805° C. to less than or equal to 825°C., or from greater than or equal to 810° C. to less than or equal to820° C., and all ranges and sub-ranges between the foregoing values. Thesoftening point was determined using the parallel plate viscosity methodof ASTM C1351M-96(2012).

From the above, glass compositions according to embodiments may beformed by any suitable method, such as slot forming, float forming,rolling processes, fusion forming processes, etc.

The glass article may be characterized by the manner in which it isformed. For instance, the glass article may be characterized asfloat-formable (i.e., formed by a float process), down-drawable and, inparticular, fusion-formable or slot-drawable (i.e., formed by a downdraw process such as a fusion draw process or a slot draw process).

Some embodiments of the glass articles described herein may be formed bya down-draw process. Down-draw processes produce glass articles having auniform thickness that possess relatively pristine surfaces. Because theaverage flexural strength of the glass article is controlled by theamount and size of surface flaws, a pristine surface that has hadminimal contact has a higher initial strength. In addition, down drawnglass articles have a very flat, smooth surface that can be used in itsfinal application without costly grinding and polishing.

Some embodiments of the glass articles may be described asfusion-formable (i.e., formable using a fusion draw process). The fusionprocess uses a drawing tank that has a channel for accepting moltenglass raw material. The channel has weirs that are open at the top alongthe length of the channel on both sides of the channel. When the channelfills with molten material, the molten glass overflows the weirs. Due togravity, the molten glass flows down the outside surfaces of the drawingtank as two flowing glass films. These outside surfaces of the drawingtank extend down and inwardly so that they join at an edge below thedrawing tank. The two flowing glass films join at this edge to fuse andform a single flowing glass article. The fusion draw method offers theadvantage that, because the two glass films flowing over the channelfuse together, neither of the outside surfaces of the resulting glassarticle comes in contact with any part of the apparatus. Thus, thesurface properties of the fusion drawn glass article are not affected bysuch contact.

Some embodiments of the glass articles described herein may be formed bya slot draw process. The slot draw process is distinct from the fusiondraw method. In slot draw processes, the molten raw material glass isprovided to a drawing tank. The bottom of the drawing tank has an openslot with a nozzle that extends the length of the slot. The molten glassflows through the slot/nozzle and is drawn downward as a continuousglass article and into an annealing region.

In one or more embodiments, the glass articles described herein mayexhibit an amorphous microstructure and may be substantially free ofcrystals or crystallites. In other words, the glass articles excludeglass-ceramic materials in some embodiments.

As mentioned above, in embodiments, the alkali aluminosilicate glasscompositions can be strengthened, such as by ion exchange, making aglass that is damage resistant for applications such as, but not limitedto, glass for display covers. With reference to FIG. 1, the glass has afirst region under compressive stress (e.g., first and secondcompressive layers 120, 122 in FIG. 1) extending from the surface to adepth of compression (DOC) of the glass and a second region (e.g.,central region 130 in FIG. 1) under a tensile stress or central tension(CT) extending from the DOC into the central or interior region of theglass. As used herein, DOC refers to the depth at which the stresswithin the glass article changes from compressive to tensile. At theDOC, the stress crosses from a positive (compressive) stress to anegative (tensile) stress and thus exhibits a stress value of zero.

According to the convention normally used in the art, compression orcompressive stress is expressed as a negative (<0) stress and tension ortensile stress is expressed as a positive (>0) stress. Throughout thisdescription, however, CS is expressed as a positive or absolutevalue—i.e., as recited herein, CS=|CS|. The compressive stress (CS) hasa maximum at or near the surface of the glass, and the CS varies withdistance d from the surface according to a function. Referring again toFIG. 1, a first segment 120 extends from first surface 110 to a depth d₁and a second segment 122 extends from second surface 112 to a depth d₂.Together, these segments define a compression or CS of glass 100.Compressive stress (including surface CS) is measured by surface stressmeter (FSM) using commercially available instruments such as theFSM-6000, manufactured by Orihara Industrial Co., Ltd. (Japan). Surfacestress measurements rely upon the accurate measurement of the stressoptical coefficient (SOC), which is related to the birefringence of theglass. SOC in turn is measured according to Procedure C (Glass DiscMethod) described in ASTM standard C770-16, entitled “Standard TestMethod for Measurement of Glass Stress-Optical Coefficient,” thecontents of which are incorporated herein by reference in theirentirety.

In some embodiments, the CS is from greater than or equal to 450 MPa toless than or equal to 800 MPa, such as from greater than or equal to 475MPa to less than or equal to 775 MPa, from greater than or equal to 500MPa to less than or equal to 750 MPa, from greater than or equal to 525MPa to less than or equal to 725 MPa, from greater than or equal to 550MPa to less than or equal to 700 MPa, from greater than or equal to 575MPa to less than or equal to 675 MPa, or from greater than or equal to600 MPa to less than or equal to 650 MPa, and all ranges and sub-rangesbetween the foregoing values.

In one or more embodiments, Na⁺ and K⁺ ions are exchanged into the glassarticle and the Na⁺ ions diffuse to a deeper depth into the glassarticle than the K+ ions. The depth of penetration of K⁺ ions(“Potassium DOL”) is distinguished from DOC because it represents thedepth of potassium penetration as a result of an ion exchange process.The Potassium DOL is typically less than the DOC for the articlesdescribed herein. Potassium DOL is measured using a surface stress metersuch as the commercially available FSM-6000 surface stress meter,manufactured by Orihara Industrial Co., Ltd. (Japan), which relies onaccurate measurement of the stress optical coefficient (SOC), asdescribed above with reference to the CS measurement. The Potassium DOLof each of first and second compressive layers 120, 122 is from greaterthan or equal to 5 μm to less than or equal to 45 μm, such as fromgreater than or equal to 6 μm to less than or equal to 40 μm, fromgreater than or equal to 7 μm to less than or equal to 35 μm, fromgreater than or equal to 8 μm to less than or equal to 30 μm, or fromgreater than or equal to 9 μm to less than or equal to 25 μm, and allranges and sub-rang es between the foregoing values. In embodiments, thePotassium DOL of each of the first and second compressive layers 120,122 is from greater than or equal to 6 μm to less than or equal to 45μm, from greater than or equal to 10 μm to less than or equal to 45 μm,from greater than or equal to 15 μm to less than or equal to 45 μm, fromgreater than or equal to 20 μm to less than or equal to 45 μm, or fromgreater than or equal to 25 μm to less than or equal to 45 μm, and allranges and sub-ranges between the foregoing values. In embodiments, thePotassium DOL of each of the first and second compressive layers 120,122 is from greater than or equal to 5 μm to less than or equal to 35μm, from greater than or equal to 5 μm to less than or equal to 30 μm,from greater than or equal to 5 μm to less than or equal to 25 μm, orfrom greater than or equal to 5 μm to less than or equal to 15 μm, andall ranges and sub-ranges between the foregoing values.

The compressive stress of both major surfaces (110, 112 in FIG. 1) isbalanced by stored tension in the central region (130) of the glass. Themaximum central tension (CT) and DOC values are measured using ascattered light polariscope (SCALP) technique known in the art. TheRefracted near-field (RNF) method or SCALP may be used to measure thestress profile. When the RNF method is utilized to measure the stressprofile, the maximum CT value provided by SCALP is utilized in the RNFmethod. In particular, the stress profile measured by RNF is forcebalanced and calibrated to the maximum CT value provided by a SCALPmeasurement. The RNF method is described in U.S. Pat. No. 8,854,623,entitled “Systems and methods for measuring a profile characteristic ofa glass sample”, which is incorporated herein by reference in itsentirety. In particular, the RNF method includes placing the glassarticle adjacent to a reference block, generating apolarization-switched light beam that is switched between orthogonalpolarizations at a rate of between 1 Hz and 50 Hz, measuring an amountof power in the polarization-switched light beam and generating apolarization-switched reference signal, wherein the measured amounts ofpower in each of the orthogonal polarizations are within 50% of eachother. The method further includes transmitting thepolarization-switched light beam through the glass sample and referenceblock for different depths into the glass sample, then relaying thetransmitted polarization-switched light beam to a signal photodetectorusing a relay optical system, with the signal photodetector generating apolarization-switched detector signal. The method also includes dividingthe detector signal by the reference signal to form a normalizeddetector signal and determining the profile characteristic of the glasssample from the normalized detector signal.

In embodiments, the glass composition may have a maximum CT greater thanor equal to 30 MPa, such as greater than or equal to 35 MPa, greaterthan or equal to 40 MPa, greater than or equal to 45 MPa, greater thanor equal to 50 MPa, greater than or equal to 55 MPa, greater than orequal to 60 MPa, greater than or equal to 65 MPa, greater than or equalto 70 MPa, greater than or equal to 75 MPa, greater than or equal to 80MPa, or greater than or equal to 85 MPa. In embodiments, the glasscomposition may have a maximum CT less than or equal to 100 MPa, such asless than or equal to 95 MPa, less than or equal to 90 MPa, less than orequal to 85 MPa, less than or equal to 80 MPa, less than or equal to 75MPa, less than or equal to 70 MPa, less than or equal to 65 MPa, lessthan or equal to 60 MPa, less than or equal to 55 MPa, less than orequal to 50 MPa, less than or equal to 45 MPa, or less than or equal to40 MPa. It should be understood that, in embodiments, any of the aboveranges may be combined with any other range. In embodiments, the glasscomposition may have a maximum CT from greater than or equal to 30 MPato less than or equal to 100 MPa, such as from greater than or equal to35 MPa to less than or equal to 95 MPa, from greater than or equal to 40MPa to less than or equal to 90 MPa, from greater than or equal to 45MPa to less than or equal to 85 MPa, from greater than or equal to 50MPa to less than or equal to 80 MPa, from greater than or equal to 55MPa to less than or equal to 75 MPa, or from greater than or equal to 60MPa to less than or equal to 70 MPa, and all ranges and sub-rangesbetween the foregoing values.

As noted above, DOC is measured using a scattered light polariscope(SCALP) technique known in the art. The DOC is provided in someembodiments herein as a portion of the thickness (t) of the glassarticle. In embodiments, the glass compositions may have a depth ofcompression (DOC) from greater than or equal to 0.15t to less than orequal to 0.25t, such as from greater than or equal to 0.18t to less thanor equal to 0.22t, or from greater than or equal to 0.19t to less thanor equal to 0.21t, and all ranges and sub-ranges between the foregoingvalues. In embodiments, the glass composition may have a DOC fromgreater than or equal to 0.16t to less than or equal to 0.20t, such asfrom greater than or equal to 0.17t to less than or equal to 0.25t, fromgreater than or equal to 0.18t to less than or equal to 0.25t, fromgreater than or equal to 0.19t to less than or equal to 0.25t, fromgreater than or equal to 0.20t to less than or equal to 0.25t, fromgreater than or equal to 0.21t to less than or equal to 0.25t, fromgreater than or equal to 0.22t to less than or equal to 0.25t, fromgreater than or equal to 0.23 t to less than or equal to 0.25t, or fromgreater than or equal to 0.24t to less than or equal to 0.25t, and allranges and sub-ranges between the foregoing values. In embodiments, theglass composition may have a DOC from greater than or equal to 0.15t toless than or equal to 0.24t, such as from greater than or equal to 0.15tto less than or equal to 0.23t, from greater than or equal to 0.15t toless than or equal to 0.22t, from greater than or equal to 0.15t to lessthan or equal to 0.21t, from greater than or equal to 0.15t to less thanor equal to 0.20t, from greater than or equal to 0.15t to less than orequal to 0.19t, from greater than or equal to 0.15t to less than orequal to 0.18t, from greater than or equal to 0.15t to less than orequal to 0.17t, or from greater than or equal to 0.15t to less than orequal to 0.16t, and all ranges and sub-ranges between the foregoingvalues.

Compressive stress layers may be formed in the glass by exposing theglass to an ion exchange solution. In embodiments, the ion exchangesolution may be molten nitrate salt. In embodiments, the ion exchangesolution may be molten KNO₃, molten NaNO₃, or combinations thereof. Inembodiments, the ion exchange solution may comprise about 80% moltenKNO₃, about 75% molten KNO₃, about 70% molten KNO₃, about 65% moltenKNO₃, or about 60% molten KNO₃. In embodiments, the ion exchangesolution may comprise about 20% molten NaNO₃, about 25% molten NaNO₃,about 30% molten NaNO₃, about 35% molten NaNO₃, or about 40% moltenNaNO₃. In embodiments, the ion exchange solution may comprise about 80%molten KNO₃ and about 20% molten NaNO₃, about 75% molten KNO₃ and about25% molten NaNO₃, about 70% molten KNO₃ and about 30% molten NaNO₃,about 65% molten KNO₃ and about 35% molten NaNO₃, or about 60% moltenKNO₃ and about 40% molten NaNO₃, and all ranges and sub-ranges betweenthe foregoing values. In embodiments, other sodium and potassium saltsmay be used in the ion exchange solution, such as, for example sodium orpotassium nitrites, phosphates, or sulfates. In some embodiments, theion exchange solution may include lithium salts, such as LiNO₃.

The glass composition may be exposed to the ion exchange solution bydipping a glass article made from the glass composition into a bath ofthe ion exchange solution, spraying the ion exchange solution onto aglass article made from the glass composition, or otherwise physicallyapplying the ion exchange solution to a glass article made from theglass composition. Upon exposure to the glass composition, the ionexchange solution may, according to embodiments, be at a temperaturefrom greater than or equal to 400° C. to less than or equal to 500° C.,such as from greater than or equal to 410° C. to less than or equal to490° C., from greater than or equal to 420° C. to less than or equal to480° C., from greater than or equal to 430° C. to less than or equal to470° C., or from greater than or equal to 440° C. to less than or equalto 460° C., and all ranges and sub-ranges between the foregoing values.In embodiments, the glass composition may be exposed to the ion exchangesolution for a duration from greater than or equal to 4 hours to lessthan or equal to 48 hours, such as from greater than or equal to 8 hoursto less than or equal to 44 hours, from greater than or equal to 12hours to less than or equal to 40 hours, from greater than or equal to16 hours to less than or equal to 36 hours, from greater than or equalto 20 hours to less than or equal to 32 hours, or from greater than orequal to 24 hours to less than or equal to 28 hours, and all ranges andsub-ranges between the foregoing values.

The ion exchange process may be performed in an ion exchange solutionunder processing conditions that provide an improved compressive stressprofile as disclosed, for example, in U.S. Patent ApplicationPublication No. 2016/0102011, which is incorporated herein by referencein its entirety.

After an ion exchange process is performed, it should be understood thata composition at the surface of a glass article may be different thanthe composition of the as-formed glass article (i.e., the glass articlebefore it undergoes an ion exchange process). This results from one typeof alkali metal ion in the as-formed glass, such as, for example Li⁺ orNa⁺, being replaced with larger alkali metal ions, such as, for exampleNa⁺ or K⁺, respectively. However, the glass composition at or near thecenter of the depth of the glass article will, in embodiments, stillhave the composition of the as-formed (non-ion exchanged) glass utilizedto form the glass article.

The glass articles disclosed herein may be incorporated into anotherarticle such as an article with a display (or display articles) (e.g.,consumer electronics, including mobile phones, tablets, computers,navigation systems, and the like), architectural articles,transportation articles (e.g., automobiles, trains, aircraft, sea craft,etc.), appliance articles, or any article that requires sometransparency, scratch-resistance, abrasion resistance or a combinationthereof. An exemplary article incorporating any of the glass articlesdisclosed herein is shown in FIGS. 2A and 2B. Specifically, FIGS. 2A and2B show a consumer electronic device 200 including a housing 202 havingfront 204, back 206, and side surfaces 208; electrical components (notshown) that are at least partially inside or entirely within the housingand including at least a controller, a memory, and a display 210 at oradjacent to the front surface of the housing; and a cover substrate 212at or over the front surface of the housing such that it is over thedisplay. In some embodiments, a portion of the cover substrate 212and/or a portion of housing 202 may include any of the glass articlesdisclosed herein.

A first clause comprises a glass composition comprising: from greaterthan or equal to 55.0 mol % to less than or equal to 75.0 mol % SiO₂;from greater than or equal to 8.0 mol % to less than or equal to 20.0mol % Al₂O₃; from greater than or equal to 3.0 mol % to less than orequal to 15.0 mol % Li₂O from greater than or equal to 5.0 mol % to lessthan or equal to 15.0 mol % Na₂O; and less than or equal to 1.5 mol %K₂O, wherein Al₂O₃+Li₂O is greater than 22.5 mol %, R₂O+RO is greaterthan or equal to 18.0 mol %, R₂O/Al₂O₃ is greater than or equal to 1.06,SiO₂+Al₂O₃+B₂O₃+P₂O₅ is greater than or equal to 78.0 mol %, and(SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O is greater than or equal to 8.0.

A second clause comprises a glass composition according to the firstclause, wherein Al₂O₃+Li₂O is greater than or equal to 23.0 mol %.

A third clause comprises a glass composition according to any one of thefirst and second clauses, wherein Al₂O₃+Li₂O is from greater than orequal to 23.0 mol % to less than or equal to 26.5 mol %.

A fourth clause comprises a glass composition according to any one ofthe first to third clauses, wherein R₂O+RO is from greater than or equalto 18.0 mol % to less than or equal to 23.0 mol %.

A fifth clause comprises a glass composition according to any one of thefirst to fourth clauses, wherein R₂O+RO is from greater than or equal to19.0 mol % to less than or equal to 22.0 mol %.

A sixth clause comprises a glass composition according to any one of thefirst to fifth clauses, wherein R₂O/Al₂O₃ is from greater than or equalto 1.06 to less than or equal to 2.10.

A seventh clause comprises a glass composition according to any one ofthe first to sixth clauses, wherein R₂O/Al₂O₃ is from greater than orequal to 1.10 to less than or equal to 1.90.

An eighth clause comprises a glass composition according to any one ofthe first to seventh clauses, wherein SiO₂+Al₂O₃+B₂O₃+P₂O₅ is fromgreater than or equal to 78.0 mol % to less than or equal to 85.0 mol %.

A ninth clause comprises a glass composition according to any one of thefirst to eighth clauses, wherein SiO₂+Al₂O₃+B₂O₃+P₂O₅ is from greaterthan or equal to 78.0 mol % to less than or equal to 83.0 mol %.

A tenth clause comprises a glass composition according to any one of thefirst to ninth clauses, wherein (SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O is fromgreater than or equal to 8.0 to less than or equal to 17.0.

An eleventh clause comprises a glass composition according to any one ofthe first to tenth clauses, wherein (SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O is fromgreater than or equal to 10.0 to less than or equal to 15.0.

A twelfth clause comprises a glass composition according to any one ofthe first to eleventh clauses, wherein B₂O₃+P₂O₅ is greater than 0.0 mol%.

A thirteenth clause comprises a glass article comprising: a firstsurface; a second surface opposite the first surface, wherein athickness (t) of the glass article is measured as a distance between thefirst surface and the second surface; and a compressive stress layerextending from at least one of the first surface and the second surfaceinto the thickness (t) of the glass article, wherein a central tensionof the glass article is greater than or equal to 30 MPa, the compressivestress layer has a depth of compression that is from greater than orequal to 0.15t to less than or equal to 0.25t, and the glass article isformed from a glass comprising: from greater than or equal to 55.0 mol %to less than or equal to 75.0 mol % SiO₂; from greater than or equal to8.0 mol % to less than or equal to 20.0 mol % Al₂O₃; from greater thanor equal to 3.0 mol % to less than or equal to 15.0 mol % Li₂O; fromgreater than or equal to 5.0 mol % to less than or equal to 15.0 mol %Na₂O; and less than or equal to 1.5 mol % K₂O, wherein Al₂O₃+Li₂O isgreater than 22.5 mol %, R₂O+RO is greater than or equal to 18.0 mol %,R₂O/Al₂O₃ is greater than or equal to 1.06, SiO₂+Al₂O₃+B₂O₃+P₂O₅ isgreater than or equal to 78.0 mol %, and (SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O isgreater than or equal to 8.0.

A fourteenth clause comprises a glass article according to thethirteenth clause, wherein the central tension of the glass article isgreater than or equal to 50 MPa.

A fifteenth clause comprises a glass article of any one of thethirteenth and fourteenth clauses, wherein the central tension of theglass article is greater than or equal to 80 MPa.

A sixteenth clause comprises a glass article according to any one of thethirteenth to fifteenth clauses, wherein a potassium depth of layer ofthe compressive stress layer into the thickness of the glass article isfrom greater than 5 μm to less than or equal to 45 μm.

A seventeenth clause comprises a glass article according to any one ofthe thirteenth to sixteenth clauses, wherein the glass has a liquidusviscosity from greater than or equal to 20 kP to less than 1000 kP.

An eighteenth clause comprises a glass article according to any one ofthe thirteenth to seventeenth clauses, wherein a surface compressivestress of the compressive stress layer is greater than or equal to 450MPa to less than or equal to 800 MPa.

A nineteenth clause comprises a consumer electronic product, comprising:a housing comprising a front surface, a back surface and side surfaces;electrical components at least partially within the housing, theelectrical components comprising at least a controller, a memory, and adisplay, the display at or adjacent the front surface of the housing;and a cover substrate disposed over the display, wherein at least aportion of at least one of the housing and the cover substrate comprisesthe a glass article according to any one of the thirteenth througheighteenth clauses.

A twentieth clause comprises a glass article comprising: a firstsurface; a second surface opposite the first surface, wherein athickness (t) of the glass article is measured as a distance between thefirst surface and the second surface; and a compressive stress layerextending from at least one of the first surface and the second surfaceinto the thickness (t) of the glass article, wherein a central tensionof the glass article is greater than or equal to 60 MPa, the compressivestress layer has a depth of compression that is from greater than orequal to 0.15t to less than or equal to 0.25t, and the glass article hasa composition at a center depth of the glass article comprising: fromgreater than or equal to 55.0 mol % to less than or equal to 75.0 mol %SiO₂; from greater than or equal to 8.0 mol % to less than or equal to20.0 mol % Al₂O₃; from greater than or equal to 3.0 mol % to less thanor equal to 15.0 mol % Li₂O; from greater than or equal to 5.0 mol % toless than or equal to 15.0 mol % Na₂O; and less than or equal to 1.5 mol% K₂O, wherein Al₂O₃+Li₂O is greater than 22.5 mol %, R₂O+RO is greaterthan or equal to 18.0 mol %, R₂O/Al₂O₃ is greater than or equal to 1.06,SiO₂+Al₂O₃+B₂O₃+P₂O₅ is greater than or equal to 78.0 mol %, and(SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O is greater than or equal to 8.0.

A twenty first clause comprises a glass composition comprising: fromgreater than or equal to 55.0 mol % to less than or equal to 70.0 mol %SiO₂; from greater than or equal to 10.0 mol % to less than or equal to20.0 mol % Al₂O₃; from greater than or equal to 3.0 mol % to less thanor equal to 15.0 mol % Li₂O from greater than or equal to 5.0 mol % toless than or equal to 15.0 mol % Na₂O; and less than or equal to 1.5 mol% K₂O, wherein Al₂O₃+Li₂O is greater than 22.5 mol %, R₂O+RO is greaterthan or equal to 18.0 mol %, SiO₂+Al₂O₃+B₂O₃+P₂O₅ is greater than orequal to 78.0 mol %, and (SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O is greater than orequal to 10.50.

A twenty second clause comprises a glass article comprising: a firstsurface; a second surface opposite the first surface, wherein athickness (t) of the glass article is measured as a distance between thefirst surface and the second surface; and a compressive stress layerextending from at least one of the first surface and the second surfaceinto the thickness (t) of the glass article, wherein a central tensionof the glass article is greater than or equal to 30 MPa, the compressivestress layer has a depth of compression that is from greater than orequal to 0.15t to less than or equal to 0.25t, and the glass article isformed from a glass according to the twenty first clause.

A twenty third clause comprises the glass article of the twenty secondclause, wherein the central tension of the glass article is greater thanor equal to 50 MPa.

A twenty fourth clause comprises the glass article of any one of thetwenty second and twenty third clauses, wherein the central tension ofthe glass article is greater than or equal to 80 MPa.

A twenty fifth clause comprises the glass article of any one of thetwenty second to twenty fourth clauses, wherein a potassium depth oflayer of the compressive stress layer into the thickness of the glassarticle is from greater than 5 μm to less than or equal to 45 μm.

A twenty sixth clause comprises the glass article of any one of thetwenty second to twenty fifth, wherein the glass has a liquidusviscosity from greater than or equal to 20 kP to less than 1000 kP.

A twenty seventh clause comprises the glass article of any one of thetwenty second to twenty sixth clauses, wherein a surface compressivestress of the compressive stress layer is greater than or equal to 450MPa to less than or equal to 800 MPa.

A twenty eighth clause comprises a consumer electronic product,comprising: a housing comprising a front surface, a back surface andside surfaces; electrical components at least partially within thehousing, the electrical components comprising at least a controller, amemory, and a display, the display at or adjacent the front surface ofthe housing; and a cover substrate disposed over the display, wherein atleast a portion of at least one of the housing and the cover substratecomprises the glass article of anyone of the twenty second to twentyseventh clauses.

EXAMPLES

Embodiments will be further clarified by the following examples. Itshould be understood that these examples are not limiting to theembodiments described above.

Glass compositions having components listed in Table 1 below wereprepared by conventional glass forming methods. In Table 1, allcomponents are in mol %, and various properties of the glasscompositions were measured according to the methods disclosed in thisspecification.

TABLE 1 Sample 1 2 3 4 5 6 7 8 9 10 SiO₂ 64.35 63.38 62.28 61.30 60.2859.35 64.52 63.36 62.47 61.40 Al₂O₃ 16.33 16.26 16.30 16.32 16.36 16.3416.16 16.32 16.21 16.30 P₂O₅ 0.00 0.96 1.94 2.93 3.91 4.86 0.00 0.981.91 2.93 B₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Li₂O7.19 7.27 7.35 7.39 7.39 7.39 7.53 7.71 7.79 7.83 Na₂O 12.05 12.05 12.0511.99 11.97 11.99 11.70 11.53 11.54 11.46 K₂O 0.01 0.01 0.01 0.01 0.010.01 0.01 0.01 0.01 0.01 MgO 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.020.02 0.02 ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 SnO₂0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Al₂O₃ + Li₂O 23.5223.53 23.65 23.71 23.75 23.72 23.69 24.04 24.00 24.13 R₂O 19.25 19.3319.41 19.39 19.37 19.39 19.25 19.26 19.34 19.30 R₂O + RO 19.27 19.3519.43 19.40 19.40 19.41 19.27 19.28 19.36 19.32 Li₂O/Na₂O 0.60 0.60 0.610.62 0.62 0.62 0.64 0.67 0.67 0.68 SiO₂ + Al₂O₃ 80.68 79.64 78.58 77.6276.64 75.68 80.68 79.69 78.68 77.70 R₂O/Al₂O₃ 1.18 1.19 1.19 1.19 1.181.19 1.19 1.18 1.19 1.18 SiO₂ + Al₂O₃ + 80.68 80.60 80.52 80.55 80.5580.54 80.68 80.67 80.59 80.63 B₂O₃ + P₂O₅ (SiO₂ + Al₂O₃ + 11.22 11.0910.96 10.90 10.90 10.90 10.71 10.46 10.35 10.29 B₂O₃ + P₂O₅)/Li₂ODensity (g/cm³) 2.438 2.433 2.428 2.423 2.419 2.414 2.439 2.432 2.4272.423 Strain Pt. (° C.) 542 555 564 565 561 548 538 555 564 566 AnnealPt. (° C.) 591 605 614 615 611 598 586 605 615 616 Softening Pt. (° C.)836.2 848.6 854.7 858.6 854 849.3 826.2 845.1 854.7 854.2 10¹¹ Poise 674689 697 699 694 683 667 688 699 699 Temperature (° C.) CTE *10⁻⁷ 84.885.7 86.5 86 86.5 86.2 84.3 85 84.6 85 (1/° C.) Fulchers A −3.789 −3.451−3.171 −3.43 −2.873 −3.055 −3.478 −3.497 −3.161 −3.083 Fulchers B10641.6 9417.5 8603.9 9096 7750.1 8143.9 9775.3 9535.6 8556.3 8276.4Fulchers To −124.5 −21.8 44.9 18.3 107.4 78.2 −75.3 −28 45.1 71.1 200 PTemperature 1623 1615 1617 1605 1605 1599 1616 1617 1612 1608 (° C.)35000 P Temperature 1153 1156 1160 1159 1152 1150 1143 1158 1156 1156 (°C.) 200000 P Temperature 1046 1054 1060 1060 1056 1053 1038 1056 10561058 (° C.) Liquidus Viscosity 575 526 957 1067 1020 2190 452 328 458540 (kiloPoise) SOC (nm/mm/MPa) 2.88 2.908 2.92 2.917 2.959 2.927 2.8822.883 2.91 2.911 Refractive Index 1.5114 1.5094 1.5073 1.5055 1.50361.5029 1.5119 1.5098 1.5077 1.506 Young's Modulus 79.6 78.2 77.4 76.174.6 73.7 80.2 78.9 77.3 76.3 (GPa) Sample 11 12 13 14 15 16 17 18 19 20SiO₂ 60.29 59.46 64.31 63.32 62.48 61.36 60.29 59.43 59.89 60.39 Al₂O₃16.31 16.25 16.19 16.30 16.19 16.33 16.36 16.32 16.31 16.26 P₂O₅ 3.934.84 0.00 0.97 1.99 2.92 3.97 4.91 4.91 4.90 B₂O₃ 0.00 0.00 0.00 0.000.00 0.00 0.00 0.00 0.00 0.00 Li₂O 7.92 7.95 8.12 8.21 8.21 8.31 8.338.33 8.35 8.42 Na₂O 11.48 11.42 11.30 11.12 11.05 11.00 10.97 10.9410.46 9.95 K₂O 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 MgO0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 ZnO 0.00 0.00 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 SnO₂ 0.05 0.05 0.05 0.05 0.05 0.050.05 0.05 0.05 0.05 Al₂O₃ + Li₂O 24.22 24.20 24.31 24.51 24.40 24.6424.69 24.65 24.65 24.69 R₂O 19.40 19.37 19.42 19.34 19.26 19.31 19.3119.28 18.82 18.38 R₂O + RO 19.42 19.39 19.44 19.36 19.28 19.33 19.3319.30 18.84 18.40 Li₂O/Na₂O 0.69 0.70 0.72 0.74 0.74 0.76 0.76 0.76 0.800.85 SiO₂ + Al₂O₃ 76.60 75.71 80.51 79.62 78.68 77.69 76.65 75.75 76.2076.66 R₂O/Al₂O₃ 1.19 1.19 1.20 1.19 1.19 1.18 1.18 1.18 1.15 1.13 SiO₂ +Al₂O₃ + 80.53 80.56 80.51 80.59 80.67 80.62 80.62 80.65 81.11 81.55B₂O₃ + P₂O₅ (SiO₂ + Al₂O₃ + 10.17 10.13 9.92 9.81 9.83 9.70 9.68 9.689.72 9.68 B₂O₃ + P₂O₅)/Li₂O Density (g/cm³) 2.418 2.414 2.437 2.4292.425 2.42 2.417 2.413 2.409 2.404 Strain Pt. (° C.) 561 555 531 554 560565 561 552 553 557 Anneal Pt. (° C.) 610 605 579 602 610 614 611 602602 607 Softening Pt. (° C.) 851.5 849.5 815.1 842.5 846.5 855 850.6843.3 847 853 10¹¹ Poise 692 689 660 683 692 696 694 685 685 691Temperature (° C.) CTE *10⁻⁷ 86 85.8 84.3 84.1 84.2 84.9 85.4 85.1 82.781.4 (1/° C.) Fulchers A −3.564 −3.164 −3.476 −3.824 −3.254 −2.999−3.349 −3.189 −2.854 −3.191 Fulchers B 9520.9 8372.3 9779.2 10717.78803.7 8062.7 8831 8366.6 7673 8433.7 Fulchers To −45.9 58 −93.3 −150.97.6 83.2 27.2 57.3 105.4 67.4 200 P Temperature 1577 1590 1599 1599 15921604 1590 1581 1594 1603 (° C.) 35000 P Temperature 1128 1144 1126 11301137 1152 1146 1139 1143 1158 (° C.) 200000 P Temperature 1028 1047 10211024 1037 1055 1048 1043 1046 1061 (° C.) Liquidus Viscosity 424 1312223 179 206 405 536 756 474 512 (kiloPoise) SOC (nm/mm/MPa) 2.906 2.9192.865 2.892 2.912 2.922 2.931 2.941 2.935 2.966 Refractive Index 1.50411.5026 1.5126 1.5101 1.5081 1.5063 1.5048 1.5033 1.5028 1.5021 Young'sModulus 75.1 74.1 80.4 79.2 78.1 76.7 75.8 74.6 74.0 74.6 (GPa) Sample21 22 23 24 25 26 27 28 29 30 SiO₂ 59.90 60.19 59.84 60.10 61.40 61.3661.32 61.37 61.39 61.45 Al₂O₃ 16.31 16.38 16.40 16.45 16.25 16.30 16.3316.29 16.25 16.29 P₂O₅ 4.91 4.94 4.95 4.99 2.91 2.92 2.91 2.92 2.92 2.89B₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Li₂O 8.84 8.959.24 9.37 8.38 8.41 8.37 8.34 8.39 8.38 Na₂O 9.95 9.46 9.49 9.00 9.999.99 10.07 9.02 9.05 9.00 K₂O 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.010.01 0.01 MgO 0.02 0.02 0.02 0.02 1.01 0.02 0.49 2.00 0.02 1.00 ZnO 0.000.00 0.00 0.00 0.00 0.94 0.46 0.00 1.92 0.93 SnO₂ 0.05 0.05 0.05 0.050.05 0.05 0.05 0.05 0.05 0.05 Al₂O₃ + Li₂O 25.15 25.34 25.63 25.82 24.6324.71 24.69 24.64 24.64 24.66 R₂O 18.80 18.42 18.73 18.38 18.38 18.4118.44 17.37 17.45 17.39 R₂O + RO 18.82 18.44 18.75 18.40 19.39 19.3619.39 19.37 19.39 19.32 Li₂O/Na₂O 0.89 0.95 0.97 1.04 0.84 0.84 0.830.93 0.93 0.93 SiO₂ + Al₂O₃ 76.21 76.57 76.24 76.55 77.65 77.67 77.6577.66 77.64 77.74 R₂O/Al₂O₃ 1.15 1.12 1.14 1.12 1.13 1.13 1.13 1.07 1.071.07 SiO₂ + Al₂O₃ + 81.13 8151 81.19 81.55 80.56 80.59 80.56 80.58 80.5680.63 B₂O₃ + P₂O₅ (SiO₂ + Al₂O₃ + 9.18 9.11 8.79 8.70 9.61 9.58 9.639.66 8.60 9.63 B₂O₃ + P₂O₅)/Li₂O Density (g/cm³) 2.407 2.403 2.406 2.4012.421 2.435 2.425 2.422 2.448 2.436 Strain Pt. (° C.) 557 558 554 560566 562 565 573 561 565 Anneal Pt. (° C.) 606 608 604 609 615 611 614621 611 614 Softening Pt. (° C.) 843 852 843 853 856.4 854 854.8 861.8853.9 855.8 10¹¹ Poise 688 692 687 692 697 693 696 702 694 696Temperature (° C.) CTE *10⁻⁷ 82.9 80.5 81.9 79.8 81 80.1 80.6 77.6 76.376.4 (1/° C.) Fulchers A −3.407 −3.083 −3.065 −3.373 −3.386 −3.514−3.437 −3.416 −3.416 −3.247 Fulchers B 8891.5 8247.5 8041.1 8793.48767.4 9029.1 8904.5 8684 8789 8225.7 Fulchers To 25.7 63.2 83.9 47.6 4628.7 34.7 62.8 42.7 97.3 200 P Temperature 1583 1595 1582 1597 1588 15811587 1582 1580 1580 (° C.) 35000 P Temperature 1144 1145 1141 1158 11521149 1150 1154 1147 1153 (° C.) 200000 P Temperature 1047 1047 1045 10611055 1053 1054 1059 1051 1060 (° C.) Liquidus Viscosity 229 229 164 116201 212 215 132 95 82 (kiloPoise) SOC (nm/mm/MPa) 2.949 2.963 2.9322.956 2.924 2.949 2.956 2.932 2.99 2.966 Refractive Index 1.5034 1.50271.5038 1.5031 1.507 1.5084 1.5074 1.5081 1.5103 1.5091 Young's Modulus74.8 74.7 75.1 75.2 77.8 77.4 77.6 78.5 78.2 78.5 (GPa) Sample 31 32 3334 35 36 37 38 39 40 SiO₂ 61.36 61.41 61.50 61.36 61.27 61.51 70.2168.19 66.26 72.19 Al₂O₃ 16.33 16.23 16.14 16.29 16.20 16.27 9.83 11.8513.81 9.94 P₂O₅ 2.97 3.47 2.99 2.95 2.97 2.97 0.00 0.00 0.05 0.00 B₂O₃0.00 0.00 0.00 0.00 0.98 1.91 0.00 0.00 0.00 0.00 Li₂O 8.35 8.35 8.378.39 8.37 8.34 6.01 6.01 6.01 6.01 Na₂O 10.45 10.46 10.42 10.48 9.908.91 13.89 13.89 13.86 11.80 K₂O 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.010.01 0.01 MgO 0.02 0.02 0.49 0.24 0.01 0.01 0.00 0.00 0.00 0.00 ZnO 0.460.02 0.02 0.23 0.23 0.00 0.00 0.00 0.00 0.00 SnO₂ 0.06 0.05 0.05 0.050.05 0.05 0.05 0.05 0.00 0.05 Al₂O₃ + Li₂O 24.68 24.57 24.51 24.67 24.5824.62 15.84 17.86 19.82 15.95 R₂O 18.81 18.81 18.80 18.87 18.28 17.2619.91 19.91 19.88 17.82 R₂O + RO 19.28 18.85 19.31 19.35 18.53 17.2819.91 19.91 19.88 17.82 Li₂O/Na₂O 0.80 0.80 0.80 0.80 0.85 0.94 0.430.43 0.43 0.51 SiO₂ + Al₂O₃ 77.69 77.63 77.64 77.64 77.47 77.78 80.0480.04 80.07 82.13 R₂O/Al₂O₃ 1.15 1.16 1.16 1.16 1.13 1.06 2.02 1.68 1.441.79 SiO₂ + Al₂O₃ + 80.66 81.10 80.63 80.60 81.42 82.67 80.04 80.0480.12 82.13 B₂O₃ + P₂O₅ (SiO₂ + Al₂O₃ + 9.66 9.72 9.63 9.61 9.72 9.9113.32 13.32 13.33 13.67 B₂O₃ + P₂O₅)/Li₂O Density (g/cm³) 2.428 2.4142.42 2.424 2.409 2.396 2.425 2.433 2.440 2.408 Strain Pt. (° C.) 561 568565 562 552 546 458 475 499 470 Anneal Pt. (° C.) 611 618 614 612 604598 499 517 542 513 Softening Pt. (° C.) 850.4 861.2 854.4 853.3 847.5847.1 705 731 769 735 10¹¹ Poise 694 701 696 695 689 684 568 589 616 587Temperature (° C.) CTE *10⁻⁷ 82 82.7 82.7 82.2 81.1 76.9 87.1 87.7 88.280.3 (1/° C.) Fulchers A −3.507 −3.68 −3.151 −3.428 −3.51 −3.293 −1.855−2.373 −2.668 −1.950 Fulchers B 9164.8 9566 8306 8922.5 9133.7 8482.96336.7 7638.0 8386.1 6900.0 Fulchers To 13.3 −0.4 68.6 30.2 15.2 59.618.9 −55.9 −76.3 −3.6 200 P Temperature 1591 1599 1592 1588 1587 15761544 1578 1611 1620 (° C.) 35000 P Temperature 1152 1163 1148 1149 11491142 1009 1048 1086 1059 (° C.) 200000 P Temperature 1054 1065 1051 10521052 1047 904 939 976 948 (° C.) Liquidus Viscosity 195 296 308 314 253127 (kiloPoise) SOC (nm/mm/MPa) 2.936 2.939 2.933 2.925 2.978 3.0472.851 2.848 2.862 2.925 Refractive Index 1.5074 1.5052 1.5064 1.50711.5055 1.5046 1.5054 1.5073 1.5089 1.5028 Young's Modulus 77.4 76.1 77.276.7 76.5 75.3 76.1 77.2 77.6 76.3 (GPa) Sample 41 42 43 44 45 46 47 4849 50 SiO₂ 70.06 68.13 67.46 66.33 65.30 64.26 63.28 61.85 64.37 63.47Al₂O₃ 11.72 13.77 14.72 15.76 16.56 16.85 16.41 16.67 16.86 16.75 P₂O₅0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 B₂O₃ 0.00 0.00 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 Li₂O 6.01 6.01 5.71 5.67 5.69 5.835.61 5.76 5.81 5.70 Na₂O 12.15 12.03 12.03 12.16 12.37 11.94 12.37 12.3811.87 11.96 K₂O 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 MgO0.00 0.00 0.02 0.02 0.02 1.07 2.28 3.29 1.03 2.07 ZnO 0.00 0.00 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 SnO₂ 0.05 0.05 0.05 0.05 0.05 0.050.05 0.05 0.05 0.05 Al₂O₃ + Li₂O 17.73 19.78 20.43 21.43 22.25 22.6822.02 22.43 22.67 22.44 R₂O 18.17 18.05 17.75 17.84 18.07 17.77 17.9818.15 17.69 17.67 R₂O + RO 18.17 18.05 17.77 17.86 18.09 18.85 20.2621.44 18.72 19.73 Li₂O/Na₂O 0.49 0.50 0.47 0.47 0.46 0.49 0.45 0.47 0.490.48 SiO₂ + Al₂O₃ 81.78 81.90 82.19 82.09 81.86 81.11 79.69 78.51 81.2380.22 R₂O/Al₂O₃ 1.55 1.31 1.20 1.13 1.09 1.05 1.10 1.09 1.05 1.05 SiO₂ +Al₂O₃ + 81.78 81.90 82.19 82.09 81.86 81.11 79.69 78.51 81.23 80.22B₂O₃ + P₂O₅ (SiO₂ + Al₂O₃ + 13.61 13.63 14.41 14.47 14.39 13.91 14.2113.63 13.98 14.08 B₂O₃ + P₂O₅)/Li₂O Density (g/cm³) 2.418 2.424 2.4252.429 2.431 2.438 2.448 2.456 2.438 2.448 Strain Pt. (° C.) 486 517 540565 586 593 575 573 593 575 Anneal Pt. (° C.) 530 563 590 616 638 645625 622 645 625 Softening Pt. (° C.) 758 812 843.8 877.9 906.7 905 875.3860.8 905 875 10¹¹ Poise 606 643 675 703 727 733 710 704 733 710Temperature (° C.) CTE *10⁻⁷ 81.7 81.9 81.9 82.7 83.7 82.1 82.2 82.482.10 82.20 (1/° C.) Fulchers A −2.355 −3.091 −4.529 −4.374 −3.951−3.276 −3.592 −3.062 −3.276 −3.592 Fulchers B 7943.7 9648.4 13672.912400.8 10724.5 8698.3 9477.4 8016.7 8698.3 9477.4 Fulchers To −60−105.5 −318.2 −178.6 −35.9 93.6 10.3 98.2 93.6 10.3 200 P Temperature1646 1684 1684 1679 1679 1653 1619 1593 1653 1619 (° C.) 35000 PTemperature 1091 1158 1189 1212 1227 1206 1175 1152 1206 1175 (° C.)200000 P Temperature 978 1044 1073 1103 1123 1108 1076 1057 1108 1076 (°C.) Liquidus Viscosity 1472 3182 1853 1519 387 1853 1519 (kiloPoise) SOC(nm/mm/MPa) 2.909 2.930 2.944 2.944 2.938 2.918 2.873 2.858 2.918 2.873Refractive Index 1.5049 1.5066 1.5068 1.5073 1.5078 1.5100 1.5115 1.51361.5100 1.5115 Young's Modulus 76.9 77.9 78.2 78.0 78.3 79.7 79.9 80.579.7 79.9 (GPa) Sample 51 52 53 54 55 56 57 58 59 60 SiO₂ 63.29 63.3563.24 63.24 63.40 62.05 62.24 62.94 61.72 62.18 Al₂O₃ 17.46 17.86 17.0917.47 16.16 16.43 16.30 16.36 16.52 17.02 P₂O₅ 0.00 0.00 0.00 0.00 0.001.10 1.09 0.00 1.10 1.10 B₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.000.00 0.00 Li₂O 5.72 5.73 6.00 6.22 6.73 6.20 7.03 6.54 6.92 6.92 Na₂O11.93 11.93 12.00 11.97 13.64 13.08 13.27 12.93 12.60 12.71 K₂O 0.010.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 MgO 1.54 1.07 1.62 1.050.02 1.08 0.02 1.18 1.10 0.02 ZnO 0.00 0.00 0.00 0.00 0.00 0.00 0.000.00 0.00 0.00 SnO₂ 0.05 0.05 0.05 0.05 0.05 0.05 0.04 0.05 0.04 0.04Al₂O₃ + Li₂O 23.18 23.59 23.09 23.69 22.89 22.63 23.33 22.89 23.44 23.94R₂O 17.66 17.67 18.01 18.19 20.37 19.29 20.31 19.48 19.53 19.63 R₂O + RO19.20 18.74 19.62 19.24 20.39 20.38 20.33 20.65 20.62 19.66 Li₂O/Na₂O0.48 0.48 0.50 0.52 0.49 0.47 0.53 0.51 0.55 0.54 SiO₂ + Al₂O₃ 80.7581.21 80.33 80.71 79.56 78.48 78.54 79.30 78.24 79.20 R₂O/Al₂O₃ 1.010.99 1.05 1.04 1.26 1.17 1.25 1.19 1.18 1.15 SiO₂ + Al₂O₃ + 80.75 81.2180.33 80.71 79.56 79.58 79.63 79.30 79.33 80.30 B₂O₃ + P₂O₅ (SiO₂ +Al₂O₃ + 14.12 14.17 13.39 12.98 11.83 12.83 11.32 12.13 11.47 11.61B₂O₃ + P₂O₅)/Li₂O Density (g/cm³) 2.443 2.440 2.444 2.442 2.400 2.4002.400 2.400 2.400 2.400 Strain Pt. (° C.) 601 615 584 592 524 564 545546 559 573 Anneal Pt. (° C.) 654 670 637 644 571 614 593 594 608 624Softening Pt. (° C.) 908 926 889 898 800 857 828 834 846 869 10¹¹ Poise742 760 724 731 649 697 673 675 690 709 Temperature (° C.) CTE *10⁻⁷81.00 80.90 82.20 82.30 88.6 86.6 88.5 87.2 85.9 87.2 (1/° C.) FulchersA −3.607 −3.554 −3.468 −3.723 −3.311 −2.657 −3.409 −3.487 −3.067 −3.525Fulchers B 9163.8 8892.3 8990.5 9397 9487.1 7241.1 9457.1 9503.6 8245.39417.5 Fulchers To 76.5 118.3 64.2 59.4 −89.7 149.4 −55.3 −43.1 61.3 3.3200 P Temperature 1628 1637 1623 1619 1601 1610 1601 1599 1597 1620 (°C.) 35000 P Temperature 1201 1216 1186 1196 1118 1155 1134 1140 11451170 (° C.) 200000 P Temperature 1105 1123 1089 1101 1012 1059 1030 10381047 1070 (° C.) Liquidus Viscosity 1275 1401 1378 1147 207 1299 805 283906 839 (kiloPoise) SOC (nm/mm/MPa) 2.918 2.895 2.908 2.814 2.888 2.8642.852 2.864 2.888 Refractive Index 1.5111 1.5115 1.5114 1.5121 1.50881.5097 1.5122 1.5102 1.5093 Young's Modulus 80.0 80.0 80.2 79.4 78.077.9 79.6 78.8 78.3 (GPa) Sample 61 62 63 64 65 66 67 68 69 70 SiO₂62.34 62.24 62.32 62.25 62.24 62.26 61.38 60.52 59.63 58.66 Al₂O₃ 17.2517.22 17.22 17.23 17.24 17.25 16.32 16.41 16.48 16.48 P₂O₅ 1.09 1.061.04 1.05 1.06 1.05 0.93 1.93 2.91 3.93 B₂O₃ 0.00 0.00 0.00 0.00 0.000.00 0.00 0.00 0.00 0.00 Li₂O 7.14 7.56 7.70 7.30 7.57 7.80 7.00 7.087.17 7.13 Na₂O 12.11 11.84 11.64 11.70 11.42 11.18 12.71 12.47 12.2712.26 K₂O 0.01 0.01 0.01 0.40 0.40 0.40 0.52 0.50 0.49 0.49 MgO 0.020.02 0.02 0.02 0.03 0.02 1.09 1.04 1.01 1.00 ZnO 0.00 0.00 0.00 0.000.00 0.00 0.00 0.00 0.00 0.00 SnO₂ 0.05 0.05 0.04 0.04 0.05 0.04 0.050.05 0.05 0.05 Al₂O₃ + Li₂O 24.39 24.78 24.93 24.54 24.82 25.05 23.3223.48 23.65 23.61 R₂O 19.26 19.41 19.35 19.40 19.39 19.38 20.23 20.0519.93 19.88 R₂O + RO 19.28 19.44 19.37 19.42 19.41 19.40 21.33 21.0920.94 20.89 Li₂O/Na₂O 0.59 0.64 0.66 0.62 0.66 0.70 0.55 0.57 0.58 0.58SiO₂ + Al₂O₃ 79.59 79.46 79.54 79.48 79.48 79.51 77.70 76.93 76.11 75.14R₂O/Al₂O₃ 1.12 1.13 1.12 1.10 1.10 1.10 1.21 1.19 1.18 1.18 SiO₂ +Al₂O₃ + 80.68 80.51 80.59 80.53 80.54 80.55 78.63 78.86 79.02 79.07B₂O₃ + P₂O₅ (SiO₂ + Al₂O₃ + 11.29 10.65 10.46 11.03 10.64 10.33 11.2311.15 11.02 11.09 B₂O₃ + P₂O₅)/Li₂O Density (g/cm³) 2.434 2.433 2.4322.434 2.433 2.433 2.449 2.440 2.436 2.433 Strain Pt. (° C.) 585 584 590584 584 582 538 555 566 565 Anneal Pt. (° C.) 636 636 641 635 635 634586 601 609 607 Softening Pt. (° C.) 883.1 878.9 878.6 879.5 879.9 879.3817.4 836.8 846.9 844.2 10¹¹ Poise 721 721 724 720 720 720 666 680 685682 Temperature (° C.) CTE *10⁻⁷ (1/° C.) 85.6 85.9 84.8 86.6 85.4 86.190.10 90.10 90.20 90.60 Fulchers A −3.325 −3.869 −3.268 −3.432 −3.955−3.373 −3.493 −3.199 −3.556 Fulchers B 8741 10051.8 8568.8 9057.810392.1 8843.4 9216.9 8403.2 9085.3 Fulchers To 67.1 −17.3 75.5 45.5−42.4 57.3 −17.4 49.2 10.1 200 P Temperature 1621 1612 1614 1625 16191616 1573 1577 1561 (° C.) 35000 P Temperature 1178 1177 1172 1181 11801174 1129 1134 1132 (° C.) 200000 P Temperature 1080 1079 1075 1083 10801077 1031 1038 1036 (° C.) Liquidus Viscosity 788 482 512 587 604 3811530 1519 1638 (kiloPoise) SOC (nm/mm/MPa) 2.930 2.923 2.922 2.906 2.9032.897 2.823 2.877 2.880 2.880 Refractive Index 1.5093 1.5096 1.50981.5093 1.5096 1.5100 1.5113 1.5085 1.5069 1.5052 Young's Modulus 78.578.9 78.7 78.4 78.9 78.9 79.4 78.0 77.0 75.6 (GPa) Sample 71 72 73 74 7576 77 78 79 80 SiO₂ 57.73 56.66 64.38 63.28 62.39 61.36 60.45 59.4064.30 63.25 Al₂O₃ 16.49 16.46 16.17 16.28 16.25 16.31 16.30 16.27 16.1516.26 P₂O₅ 4.92 5.91 0.00 0.94 1.90 2.94 3.93 5.02 0.00 0.97 B₂O₃ 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Li₂O 7.11 7.20 8.65 8.748.77 8.81 8.83 8.81 9.25 9.29 Na₂O 12.21 12.21 10.72 10.68 10.61 10.4810.45 10.47 10.22 10.14 K₂O 0.49 0.49 0.01 0.01 0.01 0.01 0.01 0.01 0.010.01 MgO 1.00 1.01 0.02 0.02 0.02 0.02 0.02 0.02 0.02 0.02 ZnO 0.00 0.000.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 SnO₂ 0.05 0.05 0.05 0.05 0.050.05 0.00 0.01 0.05 0.05 Al₂O₃ + Li₂O 23.60 23.66 24.82 25.01 25.0225.13 25.13 25.07 25.40 25.55 R₂O 19.81 19.91 19.38 19.43 19.39 19.3119.29 19.29 19.48 19.44 R₂O + RO 20.81 20.92 19.40 19.45 19.41 19.3319.31 19.31 19.50 19.46 Li₂O/Na₂O 0.58 0.59 0.81 0.82 0.83 0.84 0.850.84 0.90 0.92 SiO₂ + Al₂O₂ 74.22 73.12 80.55 79.56 78.64 77.68 76.7575.67 80.45 79.52 R₂O/Al₂O₃ 1.17 1.18 1.20 1.19 1.19 1.18 1.18 1.19 1.211.19 SiO₂ + Al₂O₃ + 79.14 79.03 80.55 8050 80.54 80.62 80.68 80.69 80.4580.49 B₂O₃ + P₂O₅ (SiO₂ + Al₂O₃ + 11.13 10.97 9.31 9.22 9.18 9.15 9.139.16 8.70 8.66 B₂O₃ + P₂O₅)/Li₂O Density (g/cm³) 2.428 2.425 2.434 2.4292.424 2.419 2.415 2.411 2.433 2.426 Strain Pt. (° C.) 563 545 535 553563 562 560 551 535 552 Anneal Pt. (° C.) 608 591 582 600 612 611 609601 581 600 Softening Pt. (° C.) 837.6 827.1 818.1 837.4 849.8 849.2849.8 840.8 810 10¹¹ Poise 685 670 661 679 693 692 690 683 658Temperature (° C.) CTE *10⁻⁷ 90.00 90.30 83.6 83.8 83.6 84.6 84.1 84.282.7 82.5 (1/° C.) Fulchers A −3.161 −3.588 −3.826 −3.63 −2.79 −3.512−3.12 −3.28 −2.877 −3.537 Fulchers B 8180.3 9097.4 10478.8 9677.6 7575.69191.9 8193.7 8569.4 8126.3 9491.6 Fulchers To 66.5 3.9 −115.5 −39.6110.2 5.7 74.7 43.8 31 −34.9 200 P Temperature 1564 1549 1595 1592 15981587 1586 1579 1600 1591 (° C.) 35000 P Temperature 1128 1123 1136 11441143 1147 1144 1139 1126 1140 (° C.) 200000 P Temperature 1033 1027 10331044 1046 1049 1048 1042 1025 1039 (° C.) Liquidus Viscosity 2331 5458123 148 127 215 233 388 81 124 (kiloPoise) SOC (nm/mm/MPa) 2.889 2.8822.878 2.900 2.915 2.914 2.926 2.882 Refractive Index 1.5040 1.50231.5111 1.5089 1.5070 1.5055 1.5036 1.5112 Young's Modulus 74.7 73.1 79.778.5 77.2 75.8 74.7 79.8 (GPa) Sample 81 82 83 84 85 86 87 88 89 90 SiO₂62.53 61.40 60.37 59.50 64.10 63.35 62.25 61.33 60.37 59.47 Al₂O₃ 16.2816.30 16.27 16.22 16.31 16.22 16.33 16.30 16.28 16.22 P₂O₅ 1.94 2.913.93 4.87 0.00 0.94 1.95 2.88 3.89 4.85 B₂O₃ 0.00 0.00 0.00 0.00 0.000.00 0.00 0.00 0.00 0.00 Li₂O 9.11 9.27 9.31 9.34 9.83 9.76 9.86 9.919.86 9.90 Na₂O 10.06 10.03 10.03 9.99 9.68 9.64 9.55 9.49 9.52 9.48 K₂O0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 MgO 0.02 0.02 0.020.02 0.02 0.02 0.02 0.02 0.02 0.02 ZnO 0.00 0.00 0.00 0.00 0.00 0.000.00 0.00 0.00 0.00 SnO₂ 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.050.05 Al₂O₃ + Li₂O 25.39 25.57 25.58 25.56 26.14 25.99 26.18 26.21 26.1426.11 R₂O 19.17 19.31 19.34 19.34 19.52 19.41 19.41 19.41 19.39 19.38R₂O + RO 19.20 19.33 19.37 19.36 19.54 19.43 19.44 19.43 19.41 19.41Li₂O/Na₂O 0.91 0.92 0.93 0.94 1.02 1.01 1.03 1.04 1.04 1.04 SiO₂ + Al₂O₃78.81 77.70 76.65 75.73 80.41 79.58 78.57 77.64 76.65 75.69 R₂O/Al₂O₃1.18 1.18 1.19 1.19 1.20 1.20 1.19 1.19 1.19 1.19 SiO₂ + Al₂O₃ + 80.7580.62 80.58 80.59 80.41 80.52 80.52 80.52 80.54 80.54 B₂O₃ + P₂O₅(SiO₂ + Al₂O₃ + 8.87 8.69 8.66 8.63 8.18 8.25 8.17 8.13 8.17 8.14 B₂O₃ +P₂O₅)/Li₂O Density (g/cm³) 2.422 2.418 2.414 2.410 2.431 2.425 2.4202.416 2.412 2.408 Strain Pt. (° C.) 560 563 556 547 537 550 559 561 556547 Anneal Pt. (° C.) 609 612 606 596 584 599 608 610 605 597 SofteningPt. (° C.) 844.9 849.7 845.3 836.2 841.4 845 841.7 835.3 10¹¹ Poise 690693 688 677 689 691 686 679 Temperature (° C.) CTE *10⁻⁷ 82.8 83.6 83.584 81.7 81.9 82.6 82.5 83.3 83.2 (1/° C.) Fulchers A −3.174 −3.318−2.859 −3.164 −2.948 −3.471 −3.167 −2.681 −3.336 −3.133 Fulchers B8419.1 8713 7568.2 8218.3 8181 9289.7 8361.2 7083.5 8632.9 8110.1Fulchers To 56.7 38.3 114.3 68.4 32.2 −23.8 54.2 163.2 36.4 71.8 200 PTemperature 1594 1589 1581 1572 1591 1586 1583 1585 1568 1564 (° C.)35000 P Temperature 1148 1147 1137 1135 1124 1135 1139 1144 1132 1128 (°C.) 200000 P Temperature 1050 1049 1042 1039 1024 1035 1042 1051 10361033 (° C.) Liquidus Viscosity 113 122 170 218 48 68 62 92 86 74(kiloPoise) SOC (nm/mm/MPa) 2.882 2.907 2.915 2.917 2.879 2.895 2.8992.904 2.924 Refractive Index 1.5090 1.5072 1.5057 1.5042 1.5119 1.51001.5082 1.5064 1.5048 Young's Modulus 78.3 77.4 76.2 75.1 80.1 78.8 77.676.5 75.3 (GPa) Sample 91 92 93 94 95 96 97 98 99 100 SiO₂ 60.33 60.4460.38 60.32 60.45 60.35 61.46 61.49 61.41 61.38 Al₂O₃ 16.31 16.26 16.2816.26 16.27 16.23 16.26 16.26 16.23 16.25 P₂O₅ 3.92 3.88 3.95 4.00 3.914.02 2.92 2.90 2.95 2.97 B₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.000.00 0.00 Li₂O 8.38 8.43 8.37 8.33 8.45 8.39 7.80 7.85 7.87 7.85 Na₂O10.00 9.98 9.97 9.04 8.97 9.00 10.49 10.50 10.51 9.48 K₂O 0.01 0.01 0.010.01 0.01 0.01 0.01 0.01 0.01 0.01 MgO 1.01 0.02 0.50 1.99 0.02 1.011.02 0.02 0.51 2.01 ZnO 0.00 0.94 0.49 0.00 1.87 0.95 0.00 0.93 0.470.00 SnO₂ 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 0.05 Al₂O₃ + Li₂O24.69 24.68 24.65 24.59 24.72 24.62 24.06 24.11 24.10 24.10 R₂O 18.3818.42 18.35 17.38 17.43 17.40 18.30 18.35 18.39 17.34 R₂O + RO 19.3919.37 19.34 19.37 19.32 19.36 19.32 19.31 19.37 19.36 Li₂O/Na₂O 0.840.84 0.84 0.92 0.94 0.93 0.74 0.75 0.75 0.83 SiO₂ + Al₂O₃ 76.64 76.7076.66 76.58 76.73 76.57 77.71 77.74 77.64 77.62 R₂O/Al₂O₃ 1.13 1.13 1.131.07 1.07 1.07 1.13 1.13 1.13 1.07 SiO₂ + Al₂O₃ + 80.56 80.58 80.6180.58 80.63 80.59 80.63 80.65 80.59 80.59 B₂O₃ + P₂O₅ (SiO₂ + Al₂O₃ +9.62 9.56 9.63 9.67 9.54 9.60 10.33 10.28 10.24 10.26 B₂O₃ + P₂O₅)/Li₂ODensity (g/cm³) 2.418 2.430 2.423 2.418 2.444 2.430 2.422 2.436 2.4282.423 Strain Pt. (° C.) 563 555 558 568 555 560 570 564 566 575 AnnealPt. (° C.) 611 606 607.0 616 605 610 620 615 616 624 Softening Pt. (°C.) 854.9 850.1 850.4 857.2 851.8 852.1 860.4 858.1 859.7 865.6 10¹¹Poise 695 688 689 698 688 691 701 697 699 706 Temperature (° C.) CTE*10⁻⁷ 82.3 80.6 80.5 77.3 76.2 76.4 80.8 81.2 81 78.1 (1/° C.) FulchersA −3.335 −3.361 −3.421 −3.467 −3.405 −3.44 −3.108 −3.484 −3.386 −2.992Fulchers B 8633.5 8739.7 8866.5 8755.7 8753.7 8798.6 8110.4 9086.58788.5 7780.3 Fulchers To 55 39 35.9 54.3 42.8 42.9 99.8 27.8 50.7 115.7200 P Temperature 1587 1583 1585 1572 1577 1575 1599 1598 1596 1586 (°C.) 35000 P Temperature 1151 1145 1149 1147 1144 1145 1160 1160 11591148 (° C.) 200000 P Temperature 1055 1048 1052 1053 1048 1049 1064 10621062 1054 (° C.) Liquidus Viscosity 243 192 257 142 108 134 367 281 314216 (kiloPoise) SOC (nm/mm/MPa) 2.932 2.966 2.932 2.934 2.988 2.961 2.922.962 2.925 2.929 Refractive Index 1.5055 1.5067 1.5059 1.5060 1.50861.5069 1.5062 1.5075 1.5070 1.5074 Young's Modulus 76.2 76.1 76.3 77.277.1 77.2 77.0 77.3 77.2 78.2 (GPa) Sample 101 102 103 104 105 106 107108 SiO₂ 61.27 61.34 61.36 61.41 61.50 61.36 61.27 61.51 Al₂O₃ 16.2416.34 16.33 16.23 16.14 16.29 16.20 16.27 P₂O₅ 2.98 2.96 2.97 3.47 2.992.95 2.97 2.97 B₂O₃ 0.00 0.00 0.00 0.00 0.00 0.00 0.98 1.91 Li₂O 7.987.85 8.35 8.35 8.37 8.39 8.37 8.34 Na₂O 9.50 9.53 10.45 10.46 10.4210.48 9.90 8.91 K₂O 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 MgO 0.031.00 0.02 0.02 0.49 0.24 0.01 0.01 ZnO 1.94 0.93 0.46 0.02 0.02 0.230.23 0.00 SnO₂ 0.05 0.05 0.06 0.05 0.05 0.05 0.05 0.05 Al₂O₃ + Li₂O24.22 24.19 24.68 24.57 24.51 24.67 24.58 24.62 R₂O 17.49 17.39 18.8118.81 18.80 18.87 18.28 17.26 R₂O + RO 19.45 19.31 19.28 18.85 19.3119.35 18.53 17.28 Li₂O/Na₂O 0.84 0.82 0.80 0.80 0.80 0.80 0.85 0.94SiO₂ + Al₂O₃ 77.51 77.67 77.69 77.63 77.64 77.64 77.47 77.78 R₂O/Al₂O₃1.08 1.06 1.15 1.16 1.16 1.16 1.13 1.06 SiO₂ + Al₂O₃ + 80.49 80.64 80.6681.10 80.63 80.60 81.42 82.67 B₂O₃ + P₂O₅ (SiO₂ + Al₂O₃ + 10.09 10.279.66 9.72 9.63 9.61 9.72 9.91 B₂O₂ + P₂O₅)/Li₂O Density (g/cm³) 2.4492.437 2.428 2.414 2.42 2.424 2.409 2.396 Strain Pt. (° C.) 563 565 561568 565 562 552 546 Anneal Pt. (° C.) 614 615 611 618 614 612 604 598Softening Pt. (° C.) 859.2 860.8 850.4 861.2 854.4 853.3 847.5 847.110¹¹ Poise 698 699 694 701 696 695 689 684 Temperature (° C.) CTE *10⁻⁷77 76.7 82 82.7 82.7 82.2 81.1 76.9 (1/° C.) Fulchers A −3.613 −3.506−3.507 −3.68 −3.151 −3.428 −3.51 −3.293 Fulchers B 9324.8 8964.3 9164.89566 8306 8922.5 9133.7 8482.9 Fulchers To 1.6 39.9 13.3 −0.4 68.6 30.215.2 59.6 200 P Temperature 1578 1584 1591 1599 1592 1588 1587 1576 ( °C.) 35000 P Temperature 1145 1153 1152 1163 1148 1149 1149 1142 (° C.)200000 P Temperature 1048 1058 1054 1065 1051 1052 1052 1047 (° C.)Liquidus Viscosity 143 157 195 296 308 314 253 127 (kiloPoise) SOC(nm/nm/MPa) 2.987 2.963 2.936 2.939 2.933 2.925 2.978 3.047 RefractiveIndex 1.5096 1.5090 1.5074 1.5052 1.5064 1.5071 1.5055 1.5046 Young'sModulus 77.9 78.1 77.4 76.1 77.2 76.7 76.5 75.3 (GPa)

All compositional components, relationships, and ratios described inthis specification are provided in mol % unless otherwise stated. Allranges disclosed in this specification include any and all ranges andsubranges encompassed by the broadly disclosed ranges whether or notexplicitly stated before or after a range is disclosed.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the embodiments describedherein without departing from the spirit and scope of the claimedsubject matter. Thus it is intended that the specification cover themodifications and variations of the various embodiments described hereinprovided such modification and variations come within the scope of theappended claims and their equivalents.

As used herein, a trailing 0 in a number is intended to represent asignificant digit for that number. For example, the number “1.0”includes two significant digits, and the number “1.00” includes threesignificant digits.

1. A glass composition comprising: from greater than or equal to 55.0mol % to less than or equal to 75.0 mol % SiO₂; from greater than orequal to 13.0 mol % to less than or equal to 20.0 mol % Al₂O₃; fromgreater than or equal to 3.0 mol % to less than or equal to 10.0 mol %Li₂O; from greater than or equal to 5.0 mol % to less than or equal to15.0 mol % Na₂O; less than or equal to 1.5 mol % K₂O; and from greaterthan or equal to 0 mol % to less than or equal to 3.0 mol % B₂O₃,wherein: Al₂O₃+Li₂O is greater than or equal to 23.0 mol %, R₂O+RO isgreater than or equal to 18.0 mol %, where R₂O is alkali oxides presentin the glass composition and RO is divalent cation oxides present in theglass composition, R₂O/Al₂O₃ is greater than or equal to 1.06,SiO₂+Al₂O₃+B₂O₃+P₂O₅ is greater than or equal to 78.0 mol %, and(SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O is greater than or equal to 8.0. 2.(canceled)
 3. The glass composition of claim 1, wherein Al₂O₃+Li₂O isfrom greater than or equal to 23.0 mol % to less than or equal to 26.5mol %.
 4. (canceled)
 5. The glass composition of claim 1, wherein R₂O+ROis from greater than or equal to 19.0 mol % to less than or equal to22.0 mol %.
 6. The glass composition of claim 1, wherein R₂O/Al₂O₃ isfrom greater than or equal to 1.06 to less than or equal to 2.10. 7.(canceled)
 8. The glass composition of claim 1, whereinSiO₂+Al₂O₃+B₂O₃+P₂O₅ is from greater than or equal to 78.0 mol % to lessthan or equal to 82.0 mol %.
 9. (canceled)
 10. The glass composition ofclaim 1, wherein (SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O is from greater than orequal to 8.0 to less than or equal to 17.0.
 11. (canceled) 12.(canceled)
 13. A glass article comprising: a first surface; a secondsurface opposite the first surface, wherein a thickness (t) of the glassarticle is measured as a distance between the first surface and thesecond surface; and a compressive stress layer extending from at leastone of the first surface and the second surface into the thickness (t)of the glass article, wherein a central tension of the glass article isgreater than or equal to 30 MPa, the compressive stress layer has adepth of compression that is from greater than or equal to 0.15t to lessthan or equal to 0.25t, and the glass article is formed from a glasscomprising: from greater than or equal to 55.0 mol % to less than orequal to 75.0 mol % SiO₂; from greater than or equal to 13.0 mol % toless than or equal to 20.0 mol % Al₂O₃; from greater than or equal to3.0 mol % to less than or equal to 10.0 mol % Li₂O; from greater than orequal to 5.0 mol % to less than or equal to 15.0 mol % Na₂O; and lessthan or equal to 1.5 mol % K₂O, wherein: Al₂O₃+Li₂O is greater than 23.0mol %, R₂O+RO is greater than or equal to 18.0 mol %%, where R₂O isalkali oxides present in the glass composition and RO is divalent cationoxides present in the glass composition, R₂O/Al₂O₃ is greater than orequal to 1.06, SiO₂+Al₂O₃+B₂O₃+P₂O₅ is greater than or equal to 78.0 mol%, and (SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O is greater than or equal to 8.0. 14.The glass article of claim 13, wherein the central tension of the glassarticle is greater than or equal to 50 MPa.
 15. (canceled)
 16. The glassarticle of claim 13, wherein a potassium depth of layer of thecompressive stress layer into the thickness of the glass article is fromgreater than 5 μm to less than or equal to 45 μm.
 17. The glass articleof claim 13, wherein the glass has a liquidus viscosity from greaterthan or equal to 20 kP to less than 1000 kP.
 18. The glass article ofclaim 13, wherein a surface compressive stress of the compressive stresslayer is greater than or equal to 450 MPa to less than or equal to 800MPa.
 19. A consumer electronic product, comprising: a housing comprisinga front surface, a back surface and side surfaces; electrical componentsat least partially within the housing, the electrical componentscomprising at least a controller, a memory, and a display, the displayat or adjacent the front surface of the housing; and a cover substratedisposed over the display, wherein at least a portion of at least one ofthe housing and the cover substrate comprises the glass article of claim13.
 20. (canceled)
 21. A glass composition comprising: from greater thanor equal to 55.0 mol % to less than or equal to 70.0 mol % SiO₂; fromgreater than or equal to 15.0 mol % to less than or equal to 20.0 mol %Al₂O₃; from greater than or equal to 4.0 mol % to less than or equal to9.0 mol % Li₂O; from greater than or equal to 5.0 mol % to less than orequal to 15.0 mol % Na₂O; and less than or equal to 1.5 mol % K₂O,wherein: Al₂O₃+Li₂O is greater than or equal to 24.0 mol %, R₂O+RO isgreater than or equal to 18.0 mol %%%, where R₂O is alkali oxidespresent in the glass composition and RO is divalent cation oxidespresent in the glass composition, SiO₂+Al₂O₃+B₂O₃+P₂O₅ is greater thanor equal to 78.0 mol %, and (SiO₂+Al₂O₃+B₂O₃+P₂O₅)/Li₂O is greater thanor equal to 9.0.
 22. A glass article comprising: a first surface; asecond surface opposite the first surface, wherein a thickness (t) ofthe glass article is measured as a distance between the first surfaceand the second surface; and a compressive stress layer extending from atleast one of the first surface and the second surface into the thickness(t) of the glass article, wherein a central tension of the glass articleis greater than or equal to 30 MPa, the compressive stress layer has adepth of compression that is from greater than or equal to 0.15t to lessthan or equal to 0.25t, and the glass article is formed from a glassaccording to claim
 21. 23. The glass article of claim 22, wherein thecentral tension of the glass article is greater than or equal to 50 MPa.24. (canceled)
 25. The glass article of claim 22, wherein a potassiumdepth of layer of the compressive stress layer into the thickness of theglass article is from greater than 5 μm to less than or equal to 45 μm.26. (canceled)
 27. The glass article of claim 22, wherein a surfacecompressive stress of the compressive stress layer is greater than orequal to 450 MPa to less than or equal to 800 MPa.
 28. A consumerelectronic product, comprising: a housing comprising a front surface, aback surface and side surfaces; electrical components at least partiallywithin the housing, the electrical components comprising at least acontroller, a memory, and a display, the display at or adjacent thefront surface of the housing; and a cover substrate disposed over thedisplay, wherein at least a portion of at least one of the housing andthe cover substrate comprises the glass article of claim
 22. 29. Theglass composition of claim 1, further comprising from greater than 0 mol% to less than or equal to 8.5 mol % P₂O₅.
 30. The glass composition ofclaim 21, further comprising from greater than 0 mol % to less than orequal to 8.5 mol % P₂O₅.